The purpose of this study was to develop a system for improving gait ability using the e-mail feature of a cellular phone, and to examine its effectiveness at a health class. This system was planned so that the participants could acquire a gait action known as core-stretch walking. One of the main features of this system is to send e-mails to provide guidance on the walking technique every day for 28 days. Forty-four participants in the class examined the effectiveness of this system, of whom 19 in the intervention group and 20 in the control group were analyzed. We compared the change in various measured parameters associated with gait ability (10m maximum walking time, number of steps in 10m maximum walking, 10m hurdle walking time, 10m zigzag walking time, timed up and go, and maximum step length) and with the subjects sense of walking in each group. As a result of this examination, we were able to recognize shortening of the measured figure associated with gait ability in the intervention group, as opposed to the control. Furthermore, the survey of attitude towards gait demonstrated that the intervention produced a clearer action of core-stretch walking. This system utilizing the e-mail feature of a cellular phone is suggested to have potential effectiveness for improvement of gait ability.