A projection controller controls an infrared projector to selectively and sequentially project first to third infrared lights. An imaging unit images an object in a state where the first to third infrared lights are projected so as to generate first to third frames. An image processing unit synthesizes the first to third frames to generate a frame of an image signal. The projection controller sets an interval between a first timing and a second timing shorter than an interval between the first timing and a third timing. The first timing is the middle point of the period in which the second infrared light is projected. The second timing is the middle point of the period in which the first or third infrared light is projected. The third timing is the middle point of the one frame period of the first or third frame.