diff --git a/monasca_tempest_tests/config.py b/monasca_tempest_tests/config.py
index 74c9e2f..62ebe75 100644
--- a/monasca_tempest_tests/config.py
+++ b/monasca_tempest_tests/config.py
@@ -54,5 +54,10 @@ MonitoringGroup = [
                help='monasca-log-api API version'),
     cfg.StrOpt('kibana_version',
                default='4.6.3',
-               help='Kibana version')
+               help='Kibana version'),
+    cfg.IntOpt('log_api_max_log_size',
+               default=1024 * 1024,
+               help=('Refers to payload/envelope size. This should be set '
+                     'to the same value as "[service]max_log_size" in the '
+                     'monasca-log-api configuration'))
 ]
diff --git a/monasca_tempest_tests/tests/log_api/base.py b/monasca_tempest_tests/tests/log_api/base.py
index 3df6728..58db68c 100644
--- a/monasca_tempest_tests/tests/log_api/base.py
+++ b/monasca_tempest_tests/tests/log_api/base.py
@@ -40,7 +40,10 @@ def _get_message_size(size_base):
 _SMALL_MESSAGE_SIZE = _get_message_size(0.001)
 _MEDIUM_MESSAGE_SIZE = _get_message_size(0.01)
 _LARGE_MESSAGE_SIZE = _get_message_size(0.1)
-_REJECTABLE_MESSAGE_SIZE = _get_message_size(1.1)
+# rejectable message must be larger than [service]max_log_size
+# from monasca-log-api.conf
+_reject_size = CONF.monitoring.log_api_max_log_size/_ONE_MB + 0.1
+_REJECTABLE_MESSAGE_SIZE = _get_message_size(_reject_size)
 
 
 def generate_unique_message(message=None, size=50):