To obtain a water-dispersed water-base coating compsn. which is excellent in applicability and storage stability and can form a coating film excellent in appearance (gloss, smoothness, etc.), resistances to boiling water and gasoline, impact strength, etc., by compounding a specific water-base dispersion of an acrylic block copolymer with an amino resin.

Ths compsn. contains 100 pts.wt. water-base dispersion and 5-60 pts.wt. amino resin (e.g. Cymel). The dispersion is obtd. by copolymerizing 90-40wt.% α,β-ethylenicaly unsatd. low-acid-value monomer mixture having an acid value of 5mgKOH/g or lower, a hydroxyl value of 30-150mgKOH/g, and a glass transition temperature of -20°C to 50°C and 10-60wt.% α,β- ethylenically unsatd. high-acid-value monomer mixture having an acid value of 30-50mgHOK/g, a hydroxyl value of 30-150mgKOH/g, and a glass transition temperature of -20°C to 50°C, neutralizing at least 50% of the acid value of the resultant block copolymer having an acid value of 10-40mgKOH/g, a hydroxyl value of 30-150mgKOH/g, and a glass transition temperature of -20°C to 50°C with a basic substance, and dispersing the block copolymer in water.