This paper describes the reason that perception technology in HRI has not given high performance enough to be used for commercial service robots. As a practical solution for better performance of perception technology, we propose a perception framework with a dedicated perception engine called a perception demon. The demon in the proposed framework constantly collects evidences and analyses them better by combining various types of individual perception components. The proposed framework enables robot makers to easily get more reliable information on humans without concerns about optimizing perception components to their robots.