Abstract: The present invention is a material for forming an adhesive film for an adhesive film formed directly under a resist upper layer film, includes: (A) a resin having a structural unit containing an acid-dissociable group and having two or more units represented by the formula (1) where R1 represents a hydrogen atom or a methyl group, and R2 represents a group selected from the formulae (I-1) to (I-3); and (C) an organic solvent, and the material comprises (B) a photo-acid generator and/or the resin (A) having the photo-acid generating unit. This provides a material for forming an adhesive film in a fine patterning process by a multilayer resist method, where the material gives an adhesive film with high adhesiveness to a resist upper layer film, suppresses fine pattern collapse, and can form an excellent pattern profile; a patterning process using the material; and a method for forming the adhesive film.