We investigated how automatic⁄controlled process affect output monitoring under the condition where action phrases are well learned previously and dual task is performed. In fixed sequence condition, the order of action phrases was same during input session, while in random sequence condition, the order of action phrases was different. It was revealed that the fixed sequence condition enables participants to remember action phrases more easily and faster than the random condition. However, the fixed sequence condition makes the response to &ldqup;I'm not sure” more than random sequence condition in output monitoring session. We concluded that action phrases were remembered automatically as a series of actions in the fixed sequence condition and load of cognition decreased. However decreasing load of cognition made output monitoring difficult. We further discussed the output monitoring error in the relation to human error in everyday life.