A gas powered toy gun comprises a gas supplying portion from which a gas leading passage extends, a valve for controlling the gas leading passage to be open and closed selectively, a slider provided to be movable to a barrel portion connected with a bullet holding chamber and provided with a pressure receiving portion for moving backward in order to supply the bullet holding chamber with a sham bullet, a movable member having an inner space formed therein and provided to be movable in the slider so as to be put selectively in a first state wherein the inner space is coupled with the gas leading passage and in a second state wherein the inner space is removed from the gas leading passage for guiding gas flowing through the gas leading passage to the bullet holding chamber through the inner space so that the sham bullet put in the bullet holding chamber is shot with pressure of gas acting thereon and for guiding further the gas flowing through the gas leading passage to the pressure receiving portion through the inner space so that the slider is moved backward with pressure of gas acting on the pressure receiving portion, and gas flow adjusting means provided in the inner space formed in the movable member for adjusting the amount of gas flowing through the inner space to the pressure receiving portion in response to pressure of gas led into the inner space.