Abstract: A PLC unit comprises a control unit that includes a first surface of a substantially rectangular shape, where a unit-side connector is provided on a second surface that is a back surface side of the first surface, a base that includes a fixing surface having a base-side connector connected to the unit-side connector provided thereon, where a plurality of the control units are fixed on the fixing surface side by side in a lateral direction of the first surface, and a duct that is provided along a side part of the control unit on a longitudinal direction side of the first surface so as to be closer to the base side, wherein at least a part of the first surface of the control unit is constituted by a cover which is rotatably supported about an axis substantially parallel to the lateral direction of the first surface, and is openable in an area opposite to the base.