Disclosed is a resin composition which enables to form an insulating resin layer having adequate flame retardancy, while exhibiting good adhesion to a copper foil for printed wiring board production.Also disclosed is a copper foil with resin. Specifically disclosed is a resin composition for forming an insulating layer for printed wiring board, which is characterized by having a base compositioncontaining a bisphenol epoxy resin having an epoxy equivalent of not more than 200 which is in a liquid state at 25 DEG C as a component A, a linear polymer having a crosslinkable functional group asa component B, a crosslinking agent as a component C, 4,4'-diaminodiphenylsulfone or 2,2-bis(4-(4-aminophenoxy)phenyl)propane as a component D, a flame-retardant epoxy resin as a component E, and a polyfunctional epoxy resin as a component F.