A reinforcing film comprises a pressure sensitive adhesive layer laminated and fixed on a principal surface of a film substrate. The pressure sensitive adhesive layer is formed of a photocurable composition containing a photocurable agent and a base polymer having a crosslinked structure. The gel fraction of the photocurable composition is preferably 60% or more. The shear storage elastic modulus at 25° C. of the pressure sensitive adhesive layer is preferably 1×104 to 1.2×105 Pa. The shear storage elastic modulus at 25° C. of the pressure sensitive adhesive layer after photocuring is preferably 1.5×105 to 2×106 Pa.