A first connector is provided in a main body portion. A connector support mechanism is provided in an attachment unit and supports a second connector so that the second connector can be displaced along a second direction that intersects a first direction. A unit guide portion guides the attachment unit between a connection position and a position that is more separated from a main body portion than the connection position is, along the first direction, and further guides the attachment unit between the connection position and an attachment position. The connection position is a position at which the attachment unit is located when the second connector is connected to the first connector. The connector support mechanism allows the attachment unit to move between the connection position and the attachment position.