Sensuous deodorization, a method to make a person insensitive to odor by using fragrance, is a type of deodorizing method. The method relies on a person's insensitiveness, so the deodorant effect is judged by sensory evaluation. Since the subjectivity of the tester intervenes in the current sensory evaluation, it is difficult to evaluate the deodorant effect of the fragrance itself. To improve the current method, “Density Measurement Method for the Odor Cognition (DMMOC)” was established. In this method, the target odor is diluted with the fragrance, and the deodorant effect can be quantified by the dilution factor where the tester no longer cognizes the odor. Three kinds of air fresheners were examined by the current sensory evaluation and by DMMOC. Although the rank order of the deodorant effect differed in each method, the result of DMMOC corresponded with the result of the consumers' trial. This result indicates that DMMOC is effective for the evaluation of the deodorant effect.