PURPOSE: To provide an addition compound dispersing agents in which a solid after addition is never hardened into a mass, by reacting a multifunctional polyisocyanate with a hydroxyl group-containing compound and other nucleophilic reagents, and then reacting it with a basic compound containing Zerewitinoff activated hydrogen and nitrogen.

CONSTITUTION: A polyisocynate having an average functionality of 2.5-6 is reacted with a quantity reactable with 15-50% NCO group of a hydroxide group- contained compound of formula I [Y is a 8-30C (substituted) hydrocarbon or the like], reacted with a quantity reactable with 15-45% NCO group, with the total reaction quantity of NCO group 40-75%, of a compound of formula II [E is OH, NH2 or the like; (n) is 2 or 3; G is >2C hydrocarbon with a molecular weight of 3000 or less], and then reacted with a quantity reactable with the residual NCO group of a basic compound containing Zerewitinoff activated hydrogen and nitrogen of formula III [Q is OH, NH2 or the like; Z is a 2-10C hydrocarbon having tertiary amino group, (substituted) triazole or the like], whereby an addition compound with the a molecular weight of 1300-84000 having any one of formulae IV-VI [(p), (q), (r) are larger than 0, and p+q+r=2.5-6] is provided.