METHOD FOR FORMING MULTI-LAYER COATING FILM

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The present invention is to provide a method for forming a multi-layer coating film, which can combine a pre-treating step conducted for a metal substrate, before electrodeposition coating, and an electrodeposition coating step. The method comprises : a step of dipping a material to be coated in an aqueous coating composition comprising (A) a rare earth metal compound, (B) a base resin having a cationic group, and (C) a curing agent, wherein a content of the rare earth metal compound (A) in the aqueous coating composition is limited to specific range; a pre-treating step of applying a voltage of less than 50 V in the aqueous coating composition, wherein the material to be coated is used as a cathode; and an electrodeposition coating of applying a voltage of 50 to 450 V in the aqueous coating composition, wherein the material to be coated is used as a cathode.