An optical device controller, for controlling an optical device positioned in a barrel-like portion of an imitative gun facing the outside through a muzzle-like opening of the barrel-like portion. An operation controlling portion is provide for shifting the optical device from an inoperative condition to an operating condition in response to movement of a trigger-like portion, a movable valve provided on a gas leading passage for controlling the gas leading passage to be open in response to the movement of the trigger-like portion, and a sliding member having a pressure receiving portion formed therein positioned at the back of the barrel-like portion for receiving pressure of the gas coming through the gas passage formed in the gas passage forming portion and the gas leading passage which is controlled to be open by the movable valve and provided to be moved back along the barrel-like portion with the pressure of the gas acting on the pressure receiving portion.