A computer-implemented method for estimating a mental state of a target individual includes obtaining information of eye movement of the target individual in a coordinate system, in which the coordinate system determines a point representing eye movement by an angle and/or a distance with respect to a reference point that is related to a center of an object showing a scene, analyzing the information of the eye movement to extract a feature of the eye movement defined in relation to the coordinate system, and estimating the mental state of the target individual using the feature of the eye movement.