diff --git a/include/groonga/groonga.h b/include/groonga/groonga.h
index 790ca4a5ac..f3f473e543 100644
--- a/include/groonga/groonga.h
+++ b/include/groonga/groonga.h
@@ -1,5 +1,5 @@
 /*
-  Copyright(C) 2009-2016 Brazil
+  Copyright(C) 2009-2017 Brazil
 
   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
@@ -1121,6 +1121,10 @@ struct _grn_query_logger {
   void (*fin)(grn_ctx *ctx, void *user_data);
 };
 
+GRN_API grn_bool grn_query_log_flags_parse(const char *string,
+                                           int string_size,
+                                           unsigned int *flags);
+
 GRN_API grn_rc grn_query_logger_set(grn_ctx *ctx, const grn_query_logger *logger);
 GRN_API void grn_query_logger_set_flags(grn_ctx *ctx, unsigned int flags);
 GRN_API void grn_query_logger_add_flags(grn_ctx *ctx, unsigned int flags);
diff --git a/include/groonga/util.h b/include/groonga/util.h
index 9195df1ea3..0a574c665b 100644
--- a/include/groonga/util.h
+++ b/include/groonga/util.h
@@ -31,6 +31,9 @@ GRN_API grn_obj *grn_inspect_limited(grn_ctx *ctx,
 GRN_API grn_obj *grn_inspect_name(grn_ctx *ctx, grn_obj *buffer, grn_obj *obj);
 GRN_API grn_obj *grn_inspect_encoding(grn_ctx *ctx, grn_obj *buffer, grn_encoding encoding);
 GRN_API grn_obj *grn_inspect_type(grn_ctx *ctx, grn_obj *buffer, unsigned char type);
+GRN_API grn_obj *grn_inspect_query_log_flags(grn_ctx *ctx,
+                                             grn_obj *buffer,
+                                             unsigned int flags);
 
 GRN_API void grn_p(grn_ctx *ctx, grn_obj *obj);
 GRN_API void grn_p_geo_point(grn_ctx *ctx, grn_geo_point *point);
diff --git a/lib/logger.c b/lib/logger.c
index de1540b0a0..f7c8d5a075 100644
--- a/lib/logger.c
+++ b/lib/logger.c
@@ -459,6 +459,58 @@ static grn_critical_section default_query_logger_lock;
 static off_t default_query_logger_size = 0;
 static off_t default_query_logger_rotate_threshold_size = 0;
 
+grn_bool
+grn_query_log_flags_parse(const char *string,
+                          int string_size,
+                          unsigned int *flags)
+{
+  const char *string_end;
+
+  *flags = GRN_QUERY_LOG_NONE;
+
+  if (!string) {
+    return GRN_TRUE;
+  }
+
+  if (string_size < 0) {
+    string_size = strlen(string);
+  }
+
+  string_end = string + string_size;
+
+  while (string < string_end) {
+    if (*string == '|' || *string == ' ') {
+      string += 1;
+      continue;
+    }
+
+#define CHECK_FLAG(name)                                        \
+    if (((string_end - string) >= (sizeof(#name) - 1)) &&       \
+        (memcmp(string, #name, sizeof(#name) - 1) == 0) &&      \
+        (((string_end - string) == (sizeof(#name) - 1)) ||      \
+         (string[sizeof(#name) - 1] == '|') ||                  \
+         (string[sizeof(#name) - 1] == ' '))) {                 \
+      *flags |= GRN_QUERY_LOG_ ## name;                         \
+      string += sizeof(#name) - 1;                              \
+      continue;                                                 \
+    }
+
+    CHECK_FLAG(NONE);
+    CHECK_FLAG(COMMAND);
+    CHECK_FLAG(RESULT_CODE);
+    CHECK_FLAG(DESTINATION);
+    CHECK_FLAG(CACHE);
+    CHECK_FLAG(SIZE);
+    CHECK_FLAG(SCORE);
+
+#undef CHECK_FLAG
+
+    return GRN_FALSE;
+  }
+
+  return GRN_TRUE;
+}
+
 static void
 default_query_logger_log(grn_ctx *ctx, unsigned int flag,
                          const char *timestamp, const char *info,
diff --git a/lib/util.c b/lib/util.c
index cc57e2f4c6..27fc944d6a 100644
--- a/lib/util.c
+++ b/lib/util.c
@@ -248,6 +248,39 @@ grn_inspect_type(grn_ctx *ctx, grn_obj *buf, unsigned char type)
   return buf;
 }
 
+
+grn_obj *
+grn_inspect_query_log_flags(grn_ctx *ctx, grn_obj *buffer, unsigned int flags)
+{
+  grn_bool have_content = GRN_FALSE;
+
+  if (flags == GRN_QUERY_LOG_NONE) {
+    GRN_TEXT_PUTS(ctx, buffer, "NONE");
+    return buffer;
+  }
+
+#define CHECK_FLAG(NAME) do {                   \
+    if (flags & GRN_QUERY_LOG_ ## NAME) {       \
+      if (have_content) {                       \
+        GRN_TEXT_PUTS(ctx, buffer, "|");        \
+      }                                         \
+      GRN_TEXT_PUTS(ctx, buffer, #NAME);        \
+      have_content = GRN_TRUE;                  \
+    }                                           \
+  } while (GRN_FALSE)
+
+  CHECK_FLAG(COMMAND);
+  CHECK_FLAG(RESULT_CODE);
+  CHECK_FLAG(DESTINATION);
+  CHECK_FLAG(CACHE);
+  CHECK_FLAG(SIZE);
+  CHECK_FLAG(SCORE);
+
+#undef CHECK_FALG
+
+  return buffer;
+}
+
 static grn_rc
 grn_proc_inspect(grn_ctx *ctx, grn_obj *buf, grn_obj *obj)
 {