An image determination section determines whether an input image signal represents a bright image or a dark image. A control section switches between a first lighting mode in which the output of a power supply section is a first power value and a second lighting mode in which the output of power supply section is a second power value based on the determined result of the image determination section. The control section refers to a first table that contains data representing the relationship between the power value of the power supply section and the number of rotations of a cooling fan in the case in which the output of the power supply section is increased from the second power value to the first power value at a constant rate when the second lighting mode is switched to the first lighting mode.