The effects of Jajinmori Rhythm of Samulnori as a function of rhythmic auditory stimulation on the immediate activity of forearm muscle of elderly group were investigated. Ten senior members within the age range from 60 to 89 years old who reside in senior facilities located in Y city were participated in this study. The proposed experiments were carried out by comparing and analyzing the EMG data measured while the participants beat the drum under the three given conditions; i.e., 1) no external auditory stimulation 2) basic rhythm of equivalent in speed of limit cycle of participants as rhythmic auditory stimulation 3) Jajinmori Rhythm of equivalent in speed of limit cycle of participants as rhythmic auditory stimulation. The data were analyzed using one-way ANOVA. The results showed that the response of Jajinmori Rhythm, compared to that of basic rhythm, yield significant improvement in the activity of forearm muscle during beating drum. In comparison among the three given conditions, the difference between the external condition of no auditory stimulation and that of basic rhythm was not significant(p>.05). However, in the difference between Jajinmori Rhythm and no auditory stimulation, and that between Jajinmori Rhythm and basic rhythm, both showed significant differences. This behaviors are clearly indicated that the activity of forearm muscle of the elderly group is improved immediately when Jajinmori Rhythm of Samulnori, which considered as musical preferences, characteristics of rhythm and of rhythm-adapting style, is provided as a function of rhythmic auditory stimulation.