Disclosed is a developer, one that does not cause pattern collapse during the formation process, for the formation of a fine pattern and a method for pattern formation using the developer. A developer used in a lithography process includes a polymer for forming a dry-etching mask and an organic solvent. The polymer is preferably a curable resin different from a curable resin forming a resist film. The developer is preferably used after exposure of the resist film. The organic solvent in the developer is preferably butyl acetate or a mixed solvent of butyl acetate and an alcohol, or 2-pentanone or a mixed solvent of 2-pentanone and an alcohol. Also disclosed is a method for producing a semiconductor device.