diff --git a/source/src/main/java/one/nem/lacerta/source/database/entity/ToxiDocumentTagEntity.java b/source/src/main/java/one/nem/lacerta/source/database/entity/ToxiDocumentTagEntity.java
new file mode 100644
index 00000000..cf0720cf
--- /dev/null
+++ b/source/src/main/java/one/nem/lacerta/source/database/entity/ToxiDocumentTagEntity.java
@@ -0,0 +1,18 @@
+package one.nem.lacerta.source.database.entity;
+
+import androidx.room.ColumnInfo;
+import androidx.room.Entity;
+import androidx.room.PrimaryKey;
+
+@Entity(tableName = "toxi_document_tag")
+public class ToxiDocumentTagEntity {
+
+    // 複合主キー
+    @PrimaryKey
+    @ColumnInfo(name = "document_id")
+    public String documentId; // ドキュメントID
+
+    @PrimaryKey
+    @ColumnInfo(name = "tag_id")
+    public String tagId; // タグID
+}