A photo film cassette contains photo film wound in a roll form, and includes a passage port which has first and second walls between which the photo film is passed. The light-trapping fabric includes a base fabric having first and second surfaces. Pile threads are disposed to protrude from the first surface of the base fabric, for preventing ambient light from entry into the photo film cassette between the first and second walls. In the course of manufacturing the photo film cassette, before attaching the light-trapping fabric, the pile threads are previously bent in a position thereof. The light-trapping fabric is pressed against the first or second wall with a pressing roller, for attaching the second surface to the passage port. An extent of bending the pile threads is enlarged by the pressing roller during the attachment to impart a V-shape to the pile threads.