Aqueous coating material composition and method for forming multilayer coating film

An aqueous coating material composition containing a polyester resin (A), acrylic resin particles (B), a curing agent (C), and a coloring pigment (D), the aqueous coating material composition characterized in that the polyester resin (A) is a resin containing a trifunctional or higher polyfunctional polycarboxylic acid (a1) and a polyol (a2) as monomer components,

• wherein the polyol (a2) is a polyalkylene glycol (a2-1) expressed by Formula (I) below:
• HO—(X—O—)n-H (1)
• in the Formula (1), X is a straight-chain or branched hydrocarbon group with 4 carbon atoms, wherein n is a value such that a weight-average molecular weight of the polyalkylene glycol (a2-1) is 100 or greater but 5000 or smaller,
• the acrylic resin particles (B) are core-shell type acrylic resin particles (B1) each having a core part and a shell part, wherein a ratio of core parts and shell parts falls in a range of 50/50 to 90/10 based on a total quantity of monomer components, and the core parts contain, relative to a total quantity of monomer components of the core parts, 1 to 10% by mass of polymerizable unsaturated monomers having two or more polymerizable unsaturated groups in one molecule, and the composition further contains a polyether polyol (F).