There is provided a recoil shock device capable of obtaining the same recoil shock as that in a case where the weight of a piston is increased, without increasing the weight of the piston by separately providing a movable part and a weight of a piston/cylinder. There is also provided a recoil shock device capable of obtaining a recoil shock similar to that in a real gun, without damaging the outer appearance of a gun. In order to drive a weight to obtain imitated recoil, i.e., a recoil shock by operation of a movable part in a piston/cylinder which generates compressed air, a communicating part 31 which is moved in its retreating direction by the movable part 13 is provided, and a recoil spring 35 which receives a force transmitted to the weight 33 via the communicating part 31 by the movable part 13 so as to be in a compressed state is provided. A reaction that accompanies movement of the weight 33 when the recoil spring 35 is compressed and the recoil spring 35 is then extended by its resilient force is transmitted to a main body 37 of the gun.