The projection-type image display device includes a light source unit, a color generation unit provided on the optical path of emitted light from the light source unit and configured to generate multiple colors of light from emitted light from the light source in a time-division manner by rotating at a predetermined rotation cycle, a light modulation unit, and a control unit. In accordance with a color component of the input image signal, the control unit sets current values for current to be applied to the light source unit and a polarity inversion timing for inverting the polarity of the light source unit. The control unit applies current having the current values to the light source unit while inverting the polarity according to the polarity inversion timing. The control unit shifts the polarity inversion timing according to change in the current values for current to be applied to the light source unit.