diff --git a/embulk-output-jdbc/src/main/java/org/embulk/output/jdbc/setter/NStringColumnSetter.java b/embulk-output-jdbc/src/main/java/org/embulk/output/jdbc/setter/NStringColumnSetter.java
index 1138f95c..a421621c 100644
--- a/embulk-output-jdbc/src/main/java/org/embulk/output/jdbc/setter/NStringColumnSetter.java
+++ b/embulk-output-jdbc/src/main/java/org/embulk/output/jdbc/setter/NStringColumnSetter.java
@@ -61,6 +61,6 @@ public void timestampValue(final Instant v) throws IOException, SQLException
     @Override
     public void jsonValue(Value v) throws IOException, SQLException
     {
-        defaultValue.setNString();
+        batch.setNString(v.toJson());
     }
 }