The coil spring (26) of a push-out device (10) for pushing out a fuel lid toward the open direction is provided with a large pitch part (26A) and small pitch parts (26B, 26C) which have different pitches. Therefore, when the fuel lid is being closed, the increasing rate of the biasing force of the coil spring (26) when pushing a rod (20) into a case (16) at an initial stroke is smaller than the increasing rate of the biasing force at a later stroke following the initial stroke.