To enable a user to start image display without a switch operation and to prevent the image display from starting against the user's will, in an image display system including a head-mounted display.

An image display system includes: a head sensor 11 and a body sensor 12 which are put on the head and the body of a user respectively and detect turning movements of the head part and the body part respectively; a camera 13 which detects a viewing direction of the user; an image display unit 14 which displays an image within a visual field of the user; and a turning angle determination part 21 which obtains turning angles θ_V and θ_H of the head of the user on the basis of detection results of the head sensor 11 and the body sensor 12. The image display unit 14 starts image display on the basis of the viewing direction and the turning angles θ_V and θ_H of the head of the user.