Abstract: A lens-fitted photo film unit includes a front cover which covers an outside of a main body. A flash light source is secured to the main body. A sliding mechanism for switching is kept slidable on the main body, for generating a signal to actuate the flash light source. A button projection is formed to project from the sliding mechanism, and positioned externally through an opening of the front cover. A positioning projection is formed on an inside of the front cover, has an engaging surface oriented crosswise to a sliding direction of the sliding mechanism. A lock arm is disposed on the sliding mechanism, has a contact surface for engagement with the engaging surface, to lock the sliding mechanism. When the button projection is pressed toward the main body, the sliding mechanism is deformed flexibly, and unlocked by disengagement of the lock arm.

Abstract: A stopper, a stop aperture and a lens support portion are integrally formed to a lens base. The stopper hits a shutter blade when the shutter blade swings in an open direction and the shutter speed is set. The stop aperture controls light amount of subject light that passes through the taking lens and reaches the photo film. The lens support portion positions the taking lens in an optical axis direction. Position of the stopper and size of the stop aperture and position of the lens support portion are different depending on model of a lens fitted photo film unit. Each model of the lens fitted photo film unit is manufactured by selecting the lens base.