In order to create products for a user, it is necessary to implement a human center design process in the process of product development. In a human centred design process, the usability evaluation has a great importance.

In order to take the usability evaluation results effectively in to the actual product development,not only extraction of a problem but the quantitative result itself is more required. It is said that the usability is decided by the degree of “effectiveness”, “efficiency”, and “satisfaction.”

Then, in addition to the conventional protocol analysis, we developed a technique to quantify the “satisfaction” which best expresses people's feeling by using the technique of one-pair comparison (AHP: Analytic Hierarchy Process). This evaluation technique enables us to clarify the usability level of the evaluation subjects and the importance of evaluation criteria with quantitative results in accordance with the qualitative information acquired by protocol analysis.