PURPOSE: To provide the titled compsn. having excellent temporary rust proofness and corrosion proofness, consisting of finely divided specified thermosetting resin particles, a surfactant and/or a thickening agent and water.

CONSTITUTION: 0.01W5wt% (based on the amount of resin particle mentioned below) surfactant and/or thickening agent and water are added to finely divided thermosetting resin particles having an average particle size of 1W200μ, consisting of 20W80wt% mixture (A) composed of 15W95wt% polyester resin (i) having a hydroxyl value of 30W300 obtd. by reacting 1W15wt% polyhydric phenolic carboxylic acid and 85W5wt% phosphate group-contg. copolymer (ii) having a hydroxyl value of 3W150 derived from 0.01W10wt% α,β-monoethylenically unsaturated monomer contg. a phosphate group and other α,β-monoethylenically unsaturated monomer, and 80W20wt% crosslinkable copolymer (B) derived from 5W30wt% N-alkoxymethylated monomer of an α,β-monoethylenically unsaturated carboxylic acid amide and other α,β-monoethylenically unsaturated monomer. The mixture is pulverized to give particles having a particle size of 1W50μ.