A head-mounted display (HMD) may comprise: a sensor unit configured to measure the movement of a user wearing the HMD; a display unit configured to display an image; and a control unit configured to calculate the user's sightline direction from a measurement value from the sensor unit and, when the user's sightline direction satisfies a preset condition, control elements of the image other than the viewpoint using the user's sightline as a input signal. When the user's sightline direction satisfies the preset condition, the HMD controls the image, which is displayed on the HMD, using the user's sightline as an input signal, thereby performing event processing and the like without any separate controller.