To provide an electrodeposition coating compsn. which does not contain a gel even after long storage or high-temp. (40°C) storage and can form a homogeneous flat coating film excellent in stability of gloss in aging.

This compsn. contains a metal chelate compd. contg. a long- chain β-ketoester having a 6-30C alkyl ester group or the 4-ketoester together with a #-diketone. The compsn. contains (a) 50-80 wt.% component comprising at least either an acrylic resin or a fluororesin having carboxyl and hydroxyl groups, (b) 20-50 wt.% component comprising at least either an amino resin or a blocked isocyanate, and (c) 0.5-5.0 wt.% metal chelate compd. contg. the above-mentioned long-chain 4-ketoester alone or together with a β-diketone.