diff --git a/ykoiso/src/A053_RGB.java b/ykoiso/src/A053_RGB.java
new file mode 100644
index 0000000000000000000000000000000000000000..d37d197fef18cf70232bccafaed3bb46aed1de31
--- /dev/null
+++ b/ykoiso/src/A053_RGB.java
@@ -0,0 +1,101 @@
+import java.util.Scanner;
+
+public class A053_RGB {
+    // 各色を表すenum
+    enum COLOR {
+        RED("R"), BLUE("B"), GREEN("G");
+
+        final private String str;
+        private int count = 0;
+
+        COLOR(String str) {
+            this.str = str;
+        }
+
+        public String getStr() {
+            return str;
+        }
+
+        public int getCount() {
+            return count;
+        }
+
+        public void incrementCount() {
+            count++;
+        }
+
+        public static COLOR getColor(String str) {
+            for (COLOR color : COLOR.values()) {
+                if (color.getStr().equals(str)) {
+                    return color;
+                }
+            }
+            return null;
+        }
+    }
+
+    public static void main(String[] args) {
+        Scanner scan = new Scanner(System.in);
+        final int height = scan.nextInt();
+        final int width = scan.nextInt();
+
+        final String[][] map = new String[height][width];
+        // スプリットして格納
+        for (int i = 0; i < height; i++) {
+            String str = scan.next();
+            map[i] = str.split("");
+        }
+        // それぞれの色で塗った回数のカウント
+        final boolean[][] isCheck = new boolean[height][width];
+        COLOR color;
+        for (int i = 0; i < height; i++) {
+            for (int j = 0; j < width; j++) {
+                // 指定した場所が未探索かの確認
+                // 未探索なら色をカウントし隣接マスを探索
+                if (isCheck[i][j] == false) {
+                    color = COLOR.getColor(map[i][j]);
+                    color.incrementCount();
+                    checkAdjacent(i, j, map, isCheck);
+                }
+            }
+        }
+        // 結果の出力
+        System.out.println(
+                COLOR.RED.getCount() + " " + COLOR.GREEN.getCount() + " " + COLOR.BLUE.getCount());
+        scan.close();
+    }
+
+    // 同じ色で塗られている隣接マスを探索する
+    public static void checkAdjacent(final int h,final int w,final String[][] map, boolean[][] isCheck) {
+        //探索済みなら探索終了
+        if (isCheck[h][w] == true) {
+            return;
+        }
+        //対象マスを探索済みに
+        isCheck[h][w] = true;
+        //高さと幅を取得
+        final int height = map.length;
+        final int width = map[0].length;
+        //隣接マスの色を確認、同じなら再帰的に探索
+        if (w < width - 1) {
+            if (map[h][w].equals(map[h][w + 1])) {
+                checkAdjacent(h, w + 1, map, isCheck);
+            }
+        }
+        if (0 < w) {
+            if (map[h][w].equals(map[h][w - 1])) {
+                checkAdjacent(h, w - 1, map, isCheck);
+            }
+        }
+        if (h < height - 1) {
+            if (map[h][w].equals(map[h + 1][w])) {
+                checkAdjacent(h + 1, w, map, isCheck);
+            }
+        }
+        if (0 < h) {
+            if (map[h][w].equals(map[h - 1][w])) {
+                checkAdjacent(h - 1, w, map, isCheck);
+            }
+        }
+    }
+}
diff --git a/ykoiso/test/A053_RGBTest.java b/ykoiso/test/A053_RGBTest.java
new file mode 100644
index 0000000000000000000000000000000000000000..e5e7fd1c756c8a97d258f66e813a90647f976f5f
--- /dev/null
+++ b/ykoiso/test/A053_RGBTest.java
@@ -0,0 +1,135 @@
+import static org.junit.Assert.assertThat;
+import org.junit.Test;
+import static org.hamcrest.CoreMatchers.*;
+
+public class A053_RGBTest {
+    boolean[][] isCheck = new boolean[5][5];
+    final int H = 5;
+    final int W = 5;
+
+    @Test
+    public void 上下右左の方向に対して隣接した赤マスを判断できる() {
+        final String[][] map = {
+            {"G", "B", "G", "G", "G"},
+            {"G", "B", "R", "G", "G"},
+            {"G", "R", "R", "R", "G"}, 
+            {"G", "G", "R", "B", "G"}, 
+            {"G", "G", "G", "B", "G"}
+        };
+        A053_RGB.checkAdjacent(2, 2, map, isCheck);
+        final boolean[][] actual = isCheck;
+        final boolean[][] expected = {
+            {false, false, false, false, false},
+            {false, false, true , false, false}, 
+            {false, true , true , true , false},
+            {false, false, true , false, false}, 
+            {false, false, false, false, false}
+        };
+        assertThat(actual, is(expected));
+    }
+
+    @Test
+    public void 隣接したマスがない場合対象座標のみ判断する() {
+        final String[][] map = {
+            {"G", "B", "G", "G", "G"}, 
+            {"G", "B", "B", "G", "G"},
+            {"G", "G", "R", "B", "G"}, 
+            {"G", "G", "G", "B", "G"}, 
+            {"G", "G", "G", "B", "G"}
+        };
+        A053_RGB.checkAdjacent(2, 2, map, isCheck);
+        final boolean[][] actual = isCheck;
+        final boolean[][] expected = {
+            {false, false, false, false, false},
+            {false, false, false, false, false},
+            {false, false, true , false, false},
+            {false, false, false, false, false}, 
+            {false, false, false, false, false}
+        };
+        assertThat(actual, is(expected));
+    }
+
+    @Test
+    public void 斜めの位置や1つ飛ばしは隣接と判断しない() {
+        final String[][] map = {
+            {"G", "B", "R", "G", "G"}, 
+            {"R", "B", "B", "R", "G"},
+            {"G", "R", "R", "B", "G"}, 
+            {"R", "G", "G", "R", "G"}, 
+            {"G", "G", "R", "B", "G"}
+        };
+        A053_RGB.checkAdjacent(2, 2, map, isCheck);
+        final boolean[][] actual = isCheck;
+        final boolean[][] expected = {
+            {false, false, false, false, false},
+            {false, false, false, false, false}, 
+            {false, true , true , false, false},
+            {false, false, false, false, false}, 
+            {false, false, false, false, false}
+        };
+        assertThat(actual, is(expected));
+    }
+
+    @Test
+    public void 隣接した赤マスなら2つ以上連続したものでも判断できる() {
+        final String[][] map = {
+            {"R", "B", "R", "G", "G"}, 
+            {"R", "B", "R", "G", "G"},
+            {"R", "R", "R", "R", "R"}, 
+            {"G", "G", "R", "B", "R"}, 
+            {"G", "G", "G", "R", "R"}
+        };
+        A053_RGB.checkAdjacent(3, 2, map, isCheck);
+        final boolean[][] actual = isCheck;
+        final boolean[][] expected = {
+            {true , false, true , false, false},
+            {true , false, true , false, false}, 
+            {true , true , true , true , true },
+            {false, false, true , false, true }, 
+            {false, false, false, true , true }
+        };
+        assertThat(actual, is(expected));
+    }
+
+    @Test
+    public void 青マスの隣接を判断できる() {
+        final String[][] map = {
+            {"G", "B", "G", "G", "G"}, 
+            {"G", "B", "R", "G", "G"},
+            {"G", "R", "R", "R", "G"}, 
+            {"G", "G", "B", "B", "G"}, 
+            {"G", "G", "G", "B", "G"},
+        };
+        A053_RGB.checkAdjacent(3, 2, map, isCheck);
+        final boolean[][] actual = isCheck;
+        final boolean[][] expected = {
+            {false, false, false, false, false},
+            {false, false, false, false, false}, 
+            {false, false, false, false, false},
+            {false, false, true , true , false}, 
+            {false, false, false, true , false}
+        };
+        assertThat(actual, is(expected));
+    }
+
+    @Test
+    public void 緑マスの隣接を判断できる() {
+        final String[][] map = {
+            {"G", "B", "G", "G", "G"}, 
+            {"G", "B", "R", "G", "G"},
+            {"G", "R", "R", "R", "G"}, 
+            {"G", "G", "B", "B", "G"}, 
+            {"G", "G", "G", "B", "G"}
+        };
+        A053_RGB.checkAdjacent(0, 0, map, isCheck);
+        final boolean[][] actual = isCheck;
+        final boolean[][] expected = {
+            {true , false, false, false, false},
+            {true , false, false, false, false}, 
+            {true , false, false, false, false},
+            {true , true , false, false, false}, 
+            {true , true , true , false, false}
+        };
+        assertThat(actual, is(expected));
+    }
+}