To provide a shutter device for a film unit with lens which can be used even under lower-luminance environment.

As soon as a shutter sector 36 fully opens an exposure aperture 30a, a governor mechanism 44 acts on a shutter driving lever 41 and maintains the full opening of the aperture 30a so as to make exposure time longer. A switch gear 47 meshes with a gear 41c formed on the lever 41 so as to slow down the lever 41 in terms of the rotating speed. The gear 47 and an anchor 48 are mounted on a mounting plate 50 which can be retreated to a position where the gear 47 does not mesh with the gear 41c.