1. An estimation apparatus characterized by comprising: image input means for inputting image data of a user; voice input means for inputting voice data of the user; living body information input means for inputting living body information of the user; first estimation means for estimating a surrounding environment of the user on the basis of the image data, voice data, and living body information; holding means for holding reference data serving as a reference used upon estimating a psychological state of the user; second estimation means for estimating the psychological state of the user by comparing at least one of the image data, voice data, and living body information with the reference data; and third estimation means for, when the psychological state of the user estimated by said second estimation means is a predetermined state, estimating a cause of the psychological state of the user on the basis of the surrounding environment estimated by said first estimation means.