Abstract
This study was aimed to estimate changes in the people's payoff matrix, payoff difference, which must had differed significantly before and after the soap movement in Shiga Prefecture in the late 1970s with the assumption that the movement was a commons dilemma game. The changes were eventually estimated through experimental games played by university students and changes in the usage of powder soap in Shiga. As a result, it was illustrated that no band-wagon effect was observed in the above commons dilemma game, and the payoff difference must had changed at least from 5 to 2 in the game assumed in this study.
