It is an object of the present invention to provide an adhesive film which is used for producing, by a laminating method, a flexible metal-clad laminate in which the change in dimensions is suppressed, a flexible metal-clad laminate including the adhesive film, and a production method therefor. The present invention relates to an adhesive film including a polyimide film and an adhesive layer containing a thermoplastic polyimide, the adhesive layer being disposed on at least one surface of the polyimide film, a flexible metal-clad laminate produced by laminating a metal foil to the adhesive film with a thermal roll laminator, and a production method therefor, wherein the polyimide film is formed by a process including step (A) of mixing a polyamic acid solution, a dehydrating agent, and an imidization catalyst, and casting and applying the mixture onto a support to form a gel film; step (B) of stripping off the gel film and fixing both ends of the gel film; and step (C) of heating and transporting the film with both ends being fixed in a state loosened in the TD direction.