PURPOSE: To obtain uniform electrodeposited coating film and to improve the adhesion and corrosion resistance of the electrodeposited coating film by specifying the treating conditions such as the compsn. of a phosphating soln. in a soln. for phosphating as pretreatment for electrodeposition of the material to be treated of a steel or the one in which a part is composed of a galvanized steel.

CONSTITUTION: The material to be treated is first subjected to degreasing and washing by the conventional method and is thereafter activated by a titanium phosphate-contg. alkalescent aq. soln. Next, the material to be treated is brought into contact with an acidic aq. phosphating soln. contg. 1.8 to 5g/L Zn, 0.1 to 7g/L Fe (II), 8 to 25g/L P2O5 and 5 to 30g/L NO3 and in which the ratio of (free acid/total acid) is regulated to 0.04 to 0.07 at 40 to 60°C to form phosphate coating film. Furthermore, the treating soln. is preferably mixed with one or more kinds among bivalent cations composed of Mn, Mg, CO and Ni as well. Moreover, the coating film is preferably formed by the weight of 1 to 5g/m2.