In a display device (1), a light amount of laser light (L) directed from an optical filter (21) to a combiner (5) is controlled through control of a temperature of a light source (13) using temperature dependence of a wavelength of the light source (13). Accordingly, even when the display device (1) is a scanning projection type in which the combiner (5) itself is incapable of luminance adjustment, it is possible to adjust the amount of light directed to the combiner (5) according to the brightness of environmental light, and to satisfactorily ensure the visibility of a projection image displayed on the combiner (5). Further, in the display device (1), since the adjustment of the light amount is performed using the temperature dependence of the wavelength of the light source (13) instead of adjusting a power supply voltage of the light source (13), it is possible to accurately adjust the light amount of the laser light (L) directed to the combiner (5).