diff --git a/textfile.pu b/textfile.pu
new file mode 100644
index 0000000..77e11c1
--- /dev/null
+++ b/textfile.pu
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+@startuml
+title TextFile クラス階層図
+
+class TextFile {
+    - ArrayList<String> lines
+    # String EOL
+    --
+    # TextFile()
+    + static TextFile createTextFile()
+    + void save(String filename)
+    + void add(String line)
+}
+
+class WinTextFile {
+    + WinTextFile()
+}
+
+class OldMacTextFile {
+    + OldMacTextFile()
+}
+
+class LinuxTextFile {
+    + LinuxTextFile()
+}
+
+TextFile <|-- WinTextFile
+TextFile <|-- OldMacTextFile
+TextFile <|-- LinuxTextFile
+
+@enduml