To eliminate trouble that operation gets heavy in constitution for driving an opening/closing driving member engaged with the light shielding door of a film cartridge by using one toggle spring.

This film using device in which the film cartridge 200 equipped with a light shielding member 201, which can be opened/closed, at the exit of film is loaded and which is provided with the opening/closing driving member 3 driving to open/close the light shielding member is provided with plural elastic members 4 and 5 giving driving force to the opening/closing driving member in an opening operating direction where the light shielding member is driven to be opened, and set so that a position where the driving force given from the plural respective elastic members to the opening/closing driving member in the opening operating direction is maximum is made different from each other in the operating range of the opening/closing driving member driving the light shielding member between a totally opening position and a totally closing position.