PURPOSE: To quickly characterize the turbidity behavior of an alkyl polyglycoside by titrating the alkyl polyglycoside to be characterized until it becomes transparent or turbid with a reagent or measuring the turbidity after addition of the reagent.

CONSTITUTION: Titration of an alkyl polyglycoside having a formula; R-O-Zn (wherein R stands for linear or branched saturated or unsaturated alkyl residue with 8-20 carbon atoms; Zn for (oligo)glycosyl residue with n=1-5 average and containing hexose and/or pentose monomer or their mixture monomers) is carried out with a reagent in an aqueous solution state at a predetermined temperature until the solution becomes transparent or turbid. Or, the turbidity is measured after addition of the reagent. The clarification point titration of the aqueous turbid alkyl polyglycoside solution is carried out using a reagent to increase the turbidity of the alkyl polyglycoside preferably in an aqueous solution. Or, the turbidmetric titration of an aqueous transparent solution is carried out using any reagent to lower the turbidity peak preferably in an aqueous solution.