diff --git a/ykoiso/src/A023_Holiday.java b/ykoiso/src/A023_Holiday.java
new file mode 100644
index 0000000000000000000000000000000000000000..04035cb0b482f8f3132c975ee55e37c5dd78dea7
--- /dev/null
+++ b/ykoiso/src/A023_Holiday.java
@@ -0,0 +1,56 @@
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Scanner;
+
+public class A023_Holiday {
+    public static final int TWO_HOLIDAY = 5;
+
+    public static void main(String[] args) {
+        Scanner scan = new Scanner(System.in);
+        final int days = scan.nextInt();
+        final List<Integer> schedule = new ArrayList<>();
+        for (int i = 0; i < days; i++) {
+            schedule.add(scan.nextInt());
+        }
+        final int maxDaysOfTwoHoliDay = calcMaxTwoHoliday(days, schedule);
+        System.out.println(maxDaysOfTwoHoliDay);
+        scan.close();
+    }
+
+    // 週休2日の最大日数を計算
+    public static int calcMaxTwoHoliday(final int days, final List<Integer> schedule) {
+        // 週休2日の連続日数
+        int daysOfTwoHoliDay = 0;
+        // 週休2日の最大連続日数
+        int maxDaysOfTwoHoliDay = 0;
+        for (int i = 0; i < days - 6; i++) {
+            // 条件満たすなら加算
+            if (isTwoHoliday(i, schedule)) {
+                daysOfTwoHoliDay++;
+            } else {
+                // 満たさない場合リセット
+                daysOfTwoHoliDay = 0;
+            }
+            maxDaysOfTwoHoliDay=Math.max(maxDaysOfTwoHoliDay, daysOfTwoHoliDay);
+        }
+
+        // 0でないなら6日分加算
+        if (maxDaysOfTwoHoliDay != 0) {
+            maxDaysOfTwoHoliDay += 6;
+        }
+        return maxDaysOfTwoHoliDay;
+    }
+
+    // 週休2日の条件を満たすか
+    public static boolean isTwoHoliday(final int date, final List<Integer> scehdule) {
+        int workCount = 0;
+        for (int i = date; i < date + 7; i++) {
+            workCount += scehdule.get(i);
+        }
+        if (workCount <= TWO_HOLIDAY) {
+            return true;
+        } else {
+            return false;
+        }
+    }
+}
diff --git a/ykoiso/test/A023_HolidayTest.java b/ykoiso/test/A023_HolidayTest.java
new file mode 100644
index 0000000000000000000000000000000000000000..8f1b83123dfa232a1d4c5f70e44b9c76cb600005
--- /dev/null
+++ b/ykoiso/test/A023_HolidayTest.java
@@ -0,0 +1,39 @@
+import static org.junit.Assert.assertThat;
+import java.util.Arrays;
+import java.util.List;
+import org.junit.Test;
+import static org.hamcrest.CoreMatchers.*;
+
+public class A023_HolidayTest {
+    @Test
+    public void 週休2日の条件を判断できる() {
+        final List<Integer> schedule = Arrays.asList(0, 1, 1, 0, 1, 1, 1);
+        int actual = A023_Holiday.calcMaxTwoHoliday(7, schedule);
+        int expected = 7;
+        assertThat(actual, is(expected));
+    }
+
+    @Test
+    public void 条件を満たさない時0を返す() {
+        final List<Integer> schedule = Arrays.asList(1, 1, 1, 0, 1, 1, 1);
+        int actual = A023_Holiday.calcMaxTwoHoliday(7, schedule);
+        int expected = 0;
+        assertThat(actual, is(expected));
+    }
+
+    @Test
+    public void 連続した週休2日制の日数を計算できる() {
+        final List<Integer> schedule = Arrays.asList(1, 1, 1, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 1);
+        int actual = A023_Holiday.calcMaxTwoHoliday(14, schedule);
+        int expected = 13;
+        assertThat(actual, is(expected));
+    }
+    @Test
+    public void 連続していない場合カウントされない() {
+        final List<Integer> schedule = Arrays.asList(0, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 0);
+        int actual = A023_Holiday.calcMaxTwoHoliday(14, schedule);
+        int expected = 7;
+        assertThat(actual, is(expected));
+    }
+}
+