PROBLEM TO BE SOLVED: To provide a deodorant for a sludge slurry and for a dewatering cake capable of maintaining a deodorizing effect for long time exceeding 72 hours, and to provide a deodorization method using the deodorant.SOLUTION: There is provided a mixture of terminal isocyanate group-containing urethane prepolymer represented by the formula 1, where Ris a diphenylmethane diisocyanate residue, Ris a polyol group and n is an integer of 1 to 500, and polyisocyanate represented by the formula 2, where Ris a benzene ring, a cycloalkyl group having 3 to 10 carbon atoms or an aliphatic group having 2 to 10 carbon atoms and n is an integer of 0 to 50.
