To provide a norbornene-based addition polymer applicable to a cooling flow casting film forming process.

The norbornene-based addition polymer includes at least one of a repeating unit represented by general formula (1A), and at least one of a repeating unit represented by general formula (1B), (in the general formula (1A) and in the general formula (1B) R1-R4 each independently represent a hydrogen atom or a substituent, L1, L2 each independently represent a single bond or a divalent linking group, m, p each independently are an integer of 0 or 1, n, q are each independently an integer of 1-4, r, s each independently are an integer of 1-3, in the case r, s are 2 or more, R1, R3 may be same or different, A represents COOR5 or OCOR5, and R5 represents a substituent).