It is a modification apparatus (1) of a resin film (6) for making the surface of the resin film (6) hydrophilic. The modification apparatus (1) has a chamber (2), an unsaturated hydrocarbon supply device (3), and an ozone generating device (4). In the chamber (2), there are provided a supply roll (7) onto which the resin film (6) is previously wound, a take-up roll (8), and a shower head (10). While the resin film (6) wound onto the supply roll (7) is wound onto the take-up roll (8), a high-concentration ozone gas and an unsaturated hydrocarbon gas are supplied to the surface of the resin film (6) moving between the supply roll (7) and the take-up roll (8).