A first projection controller of an imaging device controls a first infrared projector, capable of projecting infrared light with multiple wavelengths, to selectively project the infrared light with the multiple wavelengths. An imaging unit of the imaging device images an object in a state where the first infrared projector projects the infrared light. A synchronous signal transmitter transmits outward a synchronous signal for synchronizing a timing of projecting infrared light from a second infrared projector controlled by a second projection controller included in another imaging device other than the imaging device, with a timing of projecting the infrared light from the first infrared projector controlled by the first projection controller.