diff --git a/engine/src/main/kotlin/com/kakao/actionbase/v2/engine/Graph.kt b/engine/src/main/kotlin/com/kakao/actionbase/v2/engine/Graph.kt
index a0771fcd..54c3e80e 100644
--- a/engine/src/main/kotlin/com/kakao/actionbase/v2/engine/Graph.kt
+++ b/engine/src/main/kotlin/com/kakao/actionbase/v2/engine/Graph.kt
@@ -182,7 +182,7 @@ class Graph(
                     Mono.fromCallable {
                         printLog(config)
 
-                        log.info("graph initialized with config: {}", config)
+                        log.info("graph initialized with config: {}", config.redacted())
                         log.info("DEFAULT_BOUNDED_ELASTIC_SIZE: {}", Schedulers.DEFAULT_BOUNDED_ELASTIC_SIZE)
                         log.info("DEFAULT_BOUNDED_ELASTIC_QUEUESIZE: {}", Schedulers.DEFAULT_BOUNDED_ELASTIC_QUEUESIZE)
 
@@ -215,7 +215,7 @@ class Graph(
             config.tenant,
             config.phase,
         )
-        log.info("graph initialized with config: {}", config)
+        log.info("graph initialized with config: {}", config.redacted())
         log.info("DEFAULT_BOUNDED_ELASTIC_SIZE: {}", Schedulers.DEFAULT_BOUNDED_ELASTIC_SIZE)
         log.info("DEFAULT_BOUNDED_ELASTIC_QUEUESIZE: {}", Schedulers.DEFAULT_BOUNDED_ELASTIC_QUEUESIZE)
     }
@@ -929,7 +929,7 @@ class Graph(
             DefaultStorageBackendFactory.initialize(config.hbase)
             log.info("phase: {}", config.phase)
             log.info("tenant: {}", config.tenant)
-            log.info("graph config: {}", config)
+            log.info("graph config: {}", config.redacted())
             log.info("kafkaClientFactory: {}", kafkaClientFactory)
             log.info("webClientFactory: {}", webClientFactory)
 
diff --git a/engine/src/main/kotlin/com/kakao/actionbase/v2/engine/GraphConfig.kt b/engine/src/main/kotlin/com/kakao/actionbase/v2/engine/GraphConfig.kt
index 2ab54cf6..ca9b51f1 100644
--- a/engine/src/main/kotlin/com/kakao/actionbase/v2/engine/GraphConfig.kt
+++ b/engine/src/main/kotlin/com/kakao/actionbase/v2/engine/GraphConfig.kt
@@ -40,9 +40,25 @@ data class GraphConfig(
     val useJdbcMetastore: Boolean = true,
     val featureFlags: List<FeatureFlags.Item> = emptyList(),
 ) {
+    /**
+     * A copy safe to log. The generated [toString] renders every field, so logging this config directly puts the
+     * metastore credentials in the log in plain text. Only the credentials are replaced - every other field stays
+     * visible, because that line is the primary record of how an instance was configured. An empty credential stays
+     * empty rather than masked, so "not configured" remains distinguishable from "configured".
+     */
+    fun redacted(): GraphConfig =
+        copy(
+            metastoreUser = mask(metastoreUser),
+            metastorePassword = mask(metastorePassword),
+        )
+
     companion object {
+        private const val MASK = "****"
+
         val builder: Builder
             get() = Builder()
+
+        private fun mask(credential: String): String = if (credential.isEmpty()) "" else MASK
     }
 
     class Builder {