Recently, the social demands for home service robots are increasing. For the development of home robots, we must consider and reduce the risk of accidents in using the robots. In this paper, we propose a new method of the robot which can reduce the risk of accidents by itself. The robot with the proposed method acts in the following way: (1) The robot explains the user about possible risks while using the desired function, (2) The user confirms to the robot that he/she understands the warning, (3) The robot recognizes the user's understanding, and then (4) The robot provides the desired function to the user. We named this method as "confirmation dialogue system". We implemented a simple prototype system as an example of the confirmation dialogue system in our home robot PaPeRo, and have collected user's feedback after some experiments. Our prototype system has demonstrated the effectiveness of this method for reducing risks in home robots.