1. A human state estimating device which estimates a human state which is at least one of a psychological state, an emotional state, and a thinking state, based on fixational eye movement of an eyeball of a user, said human state estimating device comprising: a storage unit configured to store reference data in which a human state and a reference profile are corresponded to each other, for each of plural personal attribute information, the personal attribute information indicating at least one of an age bracket, visual acuity, and illness state of a person, and the reference profile including a horizontal component which is a left-right direction component of the eyeball in a microsaccade included in normal fixational eye movement of the eyeball in the human state; a video obtaining unit configured to obtain video showing movement of the eyeball including the fixational eye movement of the eyeball of the user, the video being obtained with an eyeball rotation angle accuracy of 0.05 degrees or higher and at a measuring speed of 120 samples per second or higher; an analyzing unit configured to extract a horizontal component of a microsaccade from the fixational eye movement shown in the video, and to generate an actual-measurement profile including the extracted horizontal component; a personal attribute information obtaining unit configured to obtain personal attribute information of the user via an input unit operated by the user, the personal attribute information of the user being (i) information that is self-reported by the user and (ii) information describing a personal attribute of the user which is not measured by the human state estimating device; and an estimating unit configured to search the reference data stored in said storage unit for a reference profile which corresponds to the personal attribute information obtained by said personal attribute information obtaining unit and which is closest to the actual-measurement profile, and to determine, as the human state estimated for the user, a human state corresponding to the searched-out reference profile, the human state estimated for the user being at least one of a psychological state, an emotional state, and a thinking state.