Provided is a method for forming a multilayer coating film, comprising simultaneously curing an uncured base coating film, an uncured effect coating film, and an uncured clear coating film. In this method, an effect pigment dispersion (Y) contains water, a rheology control agent (A), and a flake-effect pigment (B), and has a solids content of 0.5 to 10 mass %; the flake-effect pigment (B) is an interference pigment in which a transparent or translucent base material is coated with a metal oxide; and the flake-effect pigment (B) is contained in an amount of 30 to 90 parts by mass based on 100 parts by mass of the total solids content in the effect pigment dispersion (Y).