To realize appropriate exposure control corresponding to diaphragm performance of an interchangeable lens without using a special device and without deteriorating image quality.

A lens interchangeable imaging apparatus can control exposure of imaging means by controlling a diaphragm and at least one of a gain and accumulation time of the imaging means in accordance with subject luminance. In a process for receiving a luminance correction amount for minimum resolution of the diaphragm and information on time between the transmission of a diaphragm control signal and the drive of the diaphragm from an interchangeable lens and for driving the diaphragm by the minimum resolution when the minimum resolution of the diaphragm is second resolution larger than first resolution, the gain or the accumulation time is changed to complement the luminance correction amount while the diaphragm is stopped, and a luminance change by the change of the gain or the accumulation time is reset at timing when the diaphragm is driven based on information on the time.