PURPOSE: To obtain the blade device which is of small inertia and prevents burn by forming the shutter blades by synthetic resin sheets and providing the shield members formed of plural fire-retardant sheets which evacuate from the opening shield position only during exposure operation.

CONSTITUTION: Blades of the blade group for opening and closing of a shutter (f) are formed at least part thereof by the molded sheets of synthetic resins and are lightweight, hence their inertia is smaller than that of metal sheets and the blades are smoothly opened and closed at smaller operating torque, resulting in smaller impact and onise. The shutter (f) is held shielded by the shield member (g) formed of fire-retardant metal sheets which retreat from the shield position in cooperation with the reflecting mirror or the like of the single-lens reflex camera only during exposure operation, whereby the occurrence of burn of the blades of the shutter (f) owing to imaging of incident light is prevented.