PURPOSE: To prevent the stripping of a film formed by galvanizing and to obtain a precoated steel plate with resistance to shearing, deformation due to an impact etc., by restricting the composition of a steel plate contg. C, Si, Mn, P, etc. and by galvanizing the steel plate to form a proper amount of a zinc layer.

CONSTITUTION: A steel plate having a composition consisting of ≤0.1% C, ≤0.1% Si, 0.1W0.5% Mn, 0.24×C%+0.005%W0.03% P and the balance Fe with inevitable impurities is galvanized to form a zinc layer by 45W120g/m2. The galvanized steel plate is kept at about 900W1,100°C to alloy the zinc layer. The resulting alloyed galvanized steel plate is subjected to a chemical conversion treatment such as phosphating or chromating, and it is coated with paint by means of a roll coater or the like. The paint is cured by heating in a hot stove or the like to obtain a precoated steel plate.