The invention provides a novel in-process release paper, i.e. a release paper used as a backing paper in the manufacturing of, e.g. a synthetic leather with a polyurethane resin. The releasing resin composition with which the release paper is coated is novel as comprising (a) a base resin selected from the group consisting of alkyd resins and acrylic resins modified with an organopolysiloxane, of which from 15 to 50% by moles of the organic groups directly bonded to the silicon atoms in a molecule are phenyl groups, having at least one hydroxy-substituted organic group directly bonded to the silicon atom in a molecule, (b) an alkanol-modified amino resin and (c) an acidic catalyst. The inventive in-process release paper is very superior to the conventional ones in the very much reduced peeling resistance, increased surface gloss and durability in repeated use.