PURPOSE: To obtain a self-developing type photographic film assembly consisting of a film unit on which a specified image is previously exposed.

CONSTITUTION: The latent image of a mark is formed on a mask 68 by exposing a 2nd part while partially masking the film unit 40 in the midst of production. The bag of liquid developer is attached to the previously exposed film unit 40 and mounted on a cassette 52 all together. The cassette 52 is loaded in a camera and a part which is not exposed previously is exposed to image carrying light while masking the previously exposed part of the film unit 40 from the image carrying light. Thereafter, the bag of the developer is allowed to pass between a pair of roller and ruptured so that the developer is extended between the layers of the film unit 40 to develop two latent images as a single photograph.