Abstract: To determine the emotion of a viewer more accurately by measuring the pupil diameter while eliminating the influence of brightness, breathing, and pulse. A reference data measuring unit measures, as reference data, a reference pupil diameter Csk, a breathing influenced pupil diameter Dskt, and a pulse influenced pupil diameter Eskt for each of various combinations of the brightness of an entire screen and the brightness of a visual point. A measuring unit identifies the reference pupil diameter Csk, the breathing influenced pupil diameter Dskt, and the pulse influenced pupil diameter Eskt corresponding to the elapsed time of content.