The present invention provides: luster coating film forming method I comprising (1) applying an aqueous luster thermosetting base coating composition (A) to a substrate in three to five stages, in such a manner that the thickness of the base coating composition (A) applied in each of the second and subsequent stages becomes 0.3 to 5 μm when cured; (2) applying a thermosetting clear coating (B) over the uncured or heat-cured coating layer of the base coating composition (A); and (3) heating the two-layer coating comprising the base coating composition (A) and clear coating composition (B) to obtain a cured two-layer coating film; and luster coating film forming method II comprising the above steps (1) to (3) and further including the step of applying and curing a thermosetting clear coating composition (C).