To increase the amount of happiness in our daily life, we must recover ourselves from displeasing emotional states and try to keep to more pleasing emotions. The way for the user to avoid displeasing emotions depends on the category of the emotion, whether it be fear, anger, disgust or sadness. In this study, we focus on emotion recognition for service robots in the living space. An emotional state is important information that allows a robot system to provide appropriate services in way that are more in tune with users' needs and preferences. Moreover, the users' emotional state can be feedbacks to evaluate user's level of satisfaction in the services. We apply a diagnosis method by using analyzed value of biological signals for the emotion recognition. Our system design is based on wireless and wearable physiological sensors for mobility and convenience of users' daily lifestyle.