Abstract: A retrofit switch apparatus is attached to a traditional switch device. The traditional switch device has a traditional switch for accepting a first user manual operation to control a target. The retrofit switch apparatus includes an attaching device, a retrofit housing and a touch module. The attaching device is attached to the traditional switch device. The retrofit housing provides a containing space for covering the traditional switch. The touch module has a touch surface and a driver circuit. The touch surface receives a second user manual operation processed by the driver circuit.