1. An image pickup device comprising: an image sensor which picks up an image of an object; a face detection unit which detects a face region from an object image picked up by the image sensor, and has a first face detection mode and a second face detection mode as operation modes, the first face detection mode and the second face detection mode having a different detection condition for detecting a face region; and a mode control unit which acquires predetermined detection information on the detection condition in the second face detection mode while the face detection unit repeats a detection operation of detecting a face region in the first face detection mode, and changes an operation mode of the face detection unit to the second face detection mode when a content of the acquired predetermined detection information satisfies the detection condition in the second face detection mode.