Method for forming multilayer coating film

A method for forming a multilayer coating film by sequentially coating an intermediate coating material composition, a base coating material composition and a clear coating material composition on a metal for a motor vehicle body, on which an electrodeposition coating material has been coated and a formed electrodeposition coating film has been completely baked, and then thermally curing, wherein the clear coating material composition is obtained by mixing a main agent (A) and a curing agent (B), the main agent (A) contains a hydroxy group-containing acrylic resin (A-1) as a main resin and a surface conditioner (A-2) at a quantity of 0.01-3.0 mass % relative to the mass of solid content in the hydroxy group-containing acrylic resin (A-1), the hydroxy group-containing acrylic resin (A-1) has a hydroxy value of 80-250 mg KOH/g, a mass average molecular weight of 1,000-30,000 and a solubility parameter (SP) value of 9.0-12.0, the surface conditioner (A-2) is a polymer which has a mass average molecular weight of 3,000-100,000 and is obtained by grafting an acrylic resin (A-2-i) and a resin (A-2-ii), the solubility parameter (SP) value of the acrylic resin (A-2-i) is 8.5-10.0, and the solubility parameter (SP) value of the resin (A-2-ii) is at least 2.0 higher than the solubility parameter (SP) value of the acrylic resin (A-2-i).