An image forming system includes: (1) an image forming apparatus and (2) a film package having a plurality of photosensitive sheet films and a light shielding bag that packs the plurality of photosensitive sheet films. Herein, the light shielding bag includes a bag section, a cut section to be cut at a first end portion of the bag section, and a holding section opposite the first end portion; after the cut section is cut, the film package is loaded on the loading section and mounted on the main body of the apparatus, the holding section is pulled from outside to take out the bag from the apparatus, and the photosensitive sheet films remain loaded on the loading section; and a length of the holding section outside the main body of the apparatus is smaller than or equal to 70 mm.