A head mounted display includes a display unit capable of transparently displaying an outside world. The head mounted display includes a processing unit that displays a moving image on the display unit； and an external sensor that detects movement in the outside world which can be transparently displayed by the display unit. The processing unit acquires the movement in the outside world obtained by the external sensor, synthesizes the acquired movement in the outside world and the moving image to be displayed, and evaluates a biological effect based on the synthesized moving image obtained by the synthesis.
