Abstract: A gun game machine wherein the player can hold a model gun in the hand away from an machine casing. This gun game machine comprises a bullet hitting optical detection unit installed in the model gun for detecting a simulated bullet hitting position, a sliding cover provided on an exposed outward portion of the gunbarrel of the model gun and slidable in the longitudinal direction of the gunbarrel section, and a cover driving means for instantaneously moving the sliding cover at high speed. The model gun and the game machine casing may be coupled to each other by means of a flexible cable containing electric conductors. The sliding cover makes a long reciprocating motion similar to the so-called blow-back movement of an actual gun, so that the player can feel a similar reaction or impact corresponding to the firing of the actual gun. This simulated firing operation also serves to attract spectators to the game.