Currently observed escalator usage in Japan is to stand on one side, which is considered as a social norm. Originally, escalator usage in Japan took the form of 'standing on both sides.' Hence escalator usage norms have changed over time. For mainly safety reasons, efforts have been made to establish 'standing on both sides' as the social norm for escalator usage. The efforts, however, have not been effective as yet and most people still 'stand on one side' when they use an escalator. This paper develops an agent-based model to reproduce the current situation observed in escalator usage expressed like in a game for extensive form and to analyze possible causes as to why 'standing on one side' has been established as the current norm based on three hypotheses and finally to examine the effectiveness of measures for changing the current norm.