The present invention is a composite stretchable film including: a surface film which is a cured product of a polyurethane 1 containing a copolymer of one or more of units “a1” to “a4” and silicone-pendant type urethane units “b1” and/or “b2” represented by the following general formula (1); and an inner film which is a cured product of a polyurethane 2 containing a unit “c” having polyether and urethane bonds represented by the following general formula (2), on which the surface film is laminated. The present invention provides a stretchable film that has excellent stretchability and strength, with the film surface having excellent water repellency, and a method for forming the same.