PROBLEM TO BE SOLVED: To provide a collagen film having stretchability so that it can follow the movement of an organ and the like.SOLUTION: The collagen film 10 comprises a first layer 11 having a plurality of collagen fibers 20 disposed along a first direction 21, and a second layer 12 having a plurality of collagen fibers 20 disposed along a second direction 22, the first layer 11 and the second layer 12 being stacked and bonded to each other. The collagen film 10 includes a first heat treatment area 31 in the form of a strip extending along a third direction 23 and a second heat treatment area 32 in the form of a strip extending along a fourth direction 24. Since the collagen film 10 has stretchability so that it can follow the movement of an organ and the like, the movement of an organ that repeats expansion and contraction, such as the stomach, the intestines, the heart or the lung, will not be hindered, and the collagen film 10 will not be ruptured.
