A self-advancing film cassette has at least one separation claw for separating a film leader from a roll of film. This separation claw is disposed within a cassette shell so that it will contact an outermost peripheral surface of a photographic film on the outer side of an area where a picture frame is to be formed. The separation claw is so configured that the contact position between the tip thereof and an end face of a film leader end is 1/3 or more of the film thickness when measured from the outer surface of the photographic film. The film leader projects most at a portion corresponding to the separation claw, and the film leader is formed to be narrow so that it will not be stuck to the film roll. In one embodiment, the film leader is subjected to deformation treatment to form a corrugated leading portion, or to rigidity increasing treatment to form a more rigid leading portion.