In a single/continuous firing air soft gun and a firing switch thereof, the air soft gun includes a gun body and a barrel fixed in the gun body, and the firing switch includes a piston seat and a firing switch device, wherein the piston seat is disposed in the gun body and capable of reciprocally moving in horizontal with respect to the barrel; and the firing switch device is installed on the piston seat, and includes a stop piece and a toggle piece connected with the stop piece, and the stop piece is disposed corresponding to the trigger assembly.