A small-sized operation switch wiring mechanism which can easily set an address without using an address setting device. The operation switch wiring mechanism includes a device body formed at three-module size. Disposed on the front surface of the device body are operation buttons which cover operators of eight operation switches individually assigned with addresses corresponding to the addresses of relays, and an operator of a rotary switch which alternatively selects a combination of the addresses of the operation switches among a plurality of combinations. In the device body, a signal processor transmits a transmission signal including operation information due to the manipulation of the operation switch, and the address of the manipulated operation switch to a signal line is received. A face cover that covers the entire front surface is detachably attached to the front surface of the device surface.