A camera body according to the present disclosure is a camera body to which a lens barrel including an optical system is detachable and reattachable, the optical system being configured to include a plurality of lenses. The camera body includes: a controller which controls the camera body; an image sensor which obtains an optical image formed by the optical system; and an image sensor driver which drives the image sensor in an optical axis direction of the optical system. The controller detects optical feature amounts of a plurality of frames in a state where the image sensor is at an identical position in the optical axis direction, detects a frame in which a change amount of an optical feature amount calculated from a plurality of the detected optical feature amounts has exceeded a predetermined threshold, and drives the image sensor driver to move the image sensor from the identical position to a reference position provided in a movable range when there is a plurality of the frames in which the change amount has exceeded the predetermined threshold.