PURPOSE: To obtain the subject composition usable as a vehicle of various paints having excellent rustproofing effect, white color capable of freely harmonizing color, inducing no environmental pollution, containing no harmful metal comprising a condensed phosphate of hardly soluble in water and zinc compound, etc.

CONSTITUTION: Condensed phosphate (preferably aluminum dihydrogen tripolyphosphate or aluminum metaphosphate) of hardly soluble in water regulating the content of particles thereof having ≥5μm particle diameter to ≤5vol.%, preferably ≤1vol.% is mixed with a zinc compound (preferably zinc oxide) and/or alkaline earth compound (e.g. carbonate, phosphate, borate or sulfate, etc., of Mg, Ca or Ba, etc.) to afford the objective composition.