Provided are an imaging device, an imaging device main body, and a focusing control method of an imaging device capable of appropriately supporting a photographer at the time of focusing. An image sensor movement driver that moves an image sensor along an optical axis is provided, and a subject is tracked by moving the image sensor within a movable range. A focusing operation detector that detects a focusing operation for the subject and a movable range switch that switches the movable range of the image sensor are provided. In a case where the focusing operation is detected by the focusing operation detector, the movable range switch widens the movable range of the image sensor.