To provide a film unit with a lens capable of magnetically recording additional data without making the film unit large in size.

A photographic film 23 with magnetic data 53 recorded by every frame is previously loaded to the film unit equipped with a lens 2 at manufacturing. The film unit equipped with the lens 2 is provided with an electromagnet 41 for erasing the magnetic data 53, and a switching knob 9 for erasing magnetic data 53 or not. When power is supplied to the electromagnetic 41, the magnetic data 53 is erased by the electromagnet 41. In accordance with the displacement of the switching knob 9, it is decided whether or not power is supplied to the electromagnet 41.