diff --git a/dsl/jpql/src/test/kotlin/com/linecorp/kotlinjdsl/dsl/jpql/expression/SubstringDslTest.kt b/dsl/jpql/src/test/kotlin/com/linecorp/kotlinjdsl/dsl/jpql/expression/SubstringDslTest.kt
new file mode 100644
index 000000000..7a511f0bf
--- /dev/null
+++ b/dsl/jpql/src/test/kotlin/com/linecorp/kotlinjdsl/dsl/jpql/expression/SubstringDslTest.kt
@@ -0,0 +1,128 @@
+package com.linecorp.kotlinjdsl.dsl.jpql.expression
+
+import com.linecorp.kotlinjdsl.dsl.jpql.queryPart
+import com.linecorp.kotlinjdsl.querymodel.jpql.expression.Expression
+import com.linecorp.kotlinjdsl.querymodel.jpql.expression.Expressions
+import org.assertj.core.api.WithAssertions
+import org.junit.jupiter.api.Test
+
+class SubstringDslTest : WithAssertions {
+    private val string1 = "string1"
+    private val int1 = 1
+    private val int2 = 2
+
+    private val stringExpression1 = Expressions.value("string1")
+    private val intExpression1 = Expressions.value(1)
+    private val intExpression2 = Expressions.value(2)
+
+    @Test
+    fun `substring() with a string and an int`() {
+        // when
+        val expression = queryPart {
+            substring(string1, int1)
+        }.toExpression()
+
+        val actual: Expression<String> = expression // for type check
+
+        // then
+        val expected = Expressions.substring(
+            value = Expressions.value(string1),
+            start = Expressions.value(int1),
+        )
+
+        assertThat(actual).isEqualTo(expected)
+    }
+
+    @Test
+    fun `substring() with a string and ints`() {
+        // when
+        val expression = queryPart {
+            substring(string1, int1, int2)
+        }.toExpression()
+
+        val actual: Expression<String> = expression // for type check
+
+        // then
+        val expected = Expressions.substring(
+            value = Expressions.value(string1),
+            start = Expressions.value(int1),
+            length = Expressions.value(int2),
+        )
+
+        assertThat(actual).isEqualTo(expected)
+    }
+
+    @Test
+    fun `substring() with a string expression and an int`() {
+        // when
+        val expression = queryPart {
+            substring(stringExpression1, int1)
+        }.toExpression()
+
+        val actual: Expression<String> = expression // for type check
+
+        // then
+        val expected = Expressions.substring(
+            value = stringExpression1,
+            start = Expressions.value(int1),
+        )
+
+        assertThat(actual).isEqualTo(expected)
+    }
+
+    @Test
+    fun `substring() with a string expression and ints`() {
+        // when
+        val expression = queryPart {
+            substring(stringExpression1, int1, int2)
+        }.toExpression()
+
+        val actual: Expression<String> = expression // for type check
+
+        // then
+        val expected = Expressions.substring(
+            value = stringExpression1,
+            start = Expressions.value(int1),
+            length = Expressions.value(int2),
+        )
+
+        assertThat(actual).isEqualTo(expected)
+    }
+
+    @Test
+    fun `substring() with a string expression and an int expression`() {
+        // when
+        val expression = queryPart {
+            substring(stringExpression1, intExpression1)
+        }.toExpression()
+
+        val actual: Expression<String> = expression // for type check
+
+        // then
+        val expected = Expressions.substring(
+            value = stringExpression1,
+            start = intExpression1,
+        )
+
+        assertThat(actual).isEqualTo(expected)
+    }
+
+    @Test
+    fun `substring() with a string expression and int expressions`() {
+        // when
+        val expression = queryPart {
+            substring(stringExpression1, intExpression1, intExpression2)
+        }.toExpression()
+
+        val actual: Expression<String> = expression // for type check
+
+        // then
+        val expected = Expressions.substring(
+            value = stringExpression1,
+            start = intExpression1,
+            length = intExpression2,
+        )
+
+        assertThat(actual).isEqualTo(expected)
+    }
+}