The present invention includes a terminal block accommodation chamber formed in a sub-plate, a cover member detachably mounted on the opening of the terminal block accommodation chamber, and a terminal block that is formed integrally with the cover member and that is loaded in and unloaded from the terminal block accommodation chamber by installing and removing the cover member. The terminal block has a plurality of feeding terminals to which leads drawn through an introduction port in the cover member are connected. A plurality of plug-shaped contact shoes for electric connection are attached to the respective terminals. Socket-shaped contact shoes leading to the solenoid valve are provided in a first connector installed inside the terminal block accommodation chamber. When the solenoid is inserted into the accommodation chamber, the contact shoes of the terminal block are connected to the contact shoes of the first connector.