An effector mounting plate is provided, which can protect wiring when carried while enabling work on the wiring. A back surface side of a plate is covered by a back case, and wiring (not shown) can be stored in a space formed between the plate and the back case. Therefore, when the plate and the back case are used as an effect pedal or carried, an external force can be prevented from acting on the wiring. Therefore, the wiring (jack) can be prevented from falling off an effector or from being forcibly bent and broken. By removing fastening screws, the back case can be removed from the plate to open the back surface side of the plate. Therefore, work on the wiring such as work of connecting/disconnecting the wiring to/from the effector and work of checking the wiring before performance can be easily performed.