diff --git a/em_oop_kawara/BaseData.java b/em_oop_kawara/BaseData.java
new file mode 100644
index 0000000..4a5fd0a
--- /dev/null
+++ b/em_oop_kawara/BaseData.java
@@ -0,0 +1,9 @@
+
+public abstract class BaseData{
+	public abstract String toString();
+	public abstract String toCSV();
+	public abstract String getPrimaryKeyValue();
+	
+	
+
+}