To provide an eco-friendly water dispersible resin composition for metal surface treatment having excellent rust preventing property, alkali resistance or the like, requiring no chromic acid and chromate based pigment, suitable to surface treatment for a galvalium steel sheet or the like, and further having excellent storage stability.

The water dispersible resin composition for metal surface treatment contains a water dispersible resin composition containing a copolymer resin emulsion obtained by subjecting a polymerizable unsaturated monomer mixture consisting of: (a) an epoxy group-containing polymerizable unsaturated monomer of 0.1 to 10 wt.%; (b) an acid group-containing polymerizable unsaturated monomer of 0.1 to 10 wt.%; and (c) other polymerizable unsaturated monomer of 80 to 99.8 wt.% to emulsion polymerization in the presence of a chain transfer agent of 0.01 to 3 wt.% to the total of the (a), (b) and (c).