1. A system using a processor for reasoning an optimized service for influencing the emotive state of a user, the system comprising: a ubiquitous system unit for collecting information about surroundings of a user, and for storing the information in database; a context awareness unit for recognizing a state of the user based on the information collected by the ubiquitous system unit, and for generating context information; a characteristic determination unit for determining characteristic information for each emotion, the characteristic information being used to determine which emotion the user feels; an emotion awareness unit for comparing the characteristic information with the at least one piece of emotion expression information, for recognizing a current emotional state of the user, and for generating emotion information; a combination unit for combining the context information and the emotion information; and a service selection unit for reasoning and selecting a service for influencing the emotive state of the user based at least in part on the combination result of the combination unit, wherein the ubiquitous system unit includes a sensor network for collecting state-related information associated with the state of the user; and a user interface for collecting at least one piece of emotion expression information expressing the emotion of the user.