When a user is about to use a new function on a robot or machinery, the user is required to: 1) understand the rules regarding the use of the function, and 2) confirm that the environment, in which the robot or machinery is operating, is suitable for the use of the new function. Failure to confirm these requirements may lead to higher accident rates, creating potentially hazardous conditions for the user. However, recognizing the level of understanding of the user and the operation condition is difficult. Therefore, we propose a method to reduce the potentially hazardous condition due to unawareness of the users by verbally communicating with the users. The new function will be initially locked, and it can only be unlocked after the user verbally confirms with the robot that he or she understands the rules and the conditions. A system was built to test the method, and experiment with users was conducted. The observational result and the following questionnaire showed effectiveness of the proposed method.