In a light source emitting single-color light represented by a solid light source such as a light emitting diode, a light output is increased while a color reproducibility is maintained. A red, a green, and a blue light emitting diode are controlled so that a first light emitting step of making the red light emitting diode emit light in a first light emission period, a second light emitting step of making the green light emitting diode emit light in a second light emission period, a third light emitting step of making the blue light emitting diode emit light in a third light emission period, and a fourth light emitting step of making the red light emitting diode, the green light emitting diode and the blue light emitting diode emit light at the same time in a fourth light emission period are carried out for display of one image.