There is provided an image taking device with removable optical unit, with which it is possible to operate the power supply of the image taking device body without operating a power switch, and operation of the power supply of the image taking device body is made easy. The image taking device with removable optical element is provided with an image taking device body, a lens unit (optical unit) that is removable with respect to the image taking device body, an attachment detection unit for detecting attachment of the lens unit to the image taking device body, and a system controller (control unit) for turning a power supply of the image taking device body on upon detection of attachment of the lens unit to the image taking device body by the attachment detection unit. The system controller is configured to turn off the power supply of the image taking device body in a state where attachment of the lens unit to the image taking device body is not detected by the attachment detection unit.