The purpose of this study was to investigate changes of isokinetic muscle strength proprioceptive function as exercise time duration after ankle taping in baseball players. For this study, thirty highschool baseball players whose had no ankle injuries were volunteered, and all subjects were randomly divided into two groups (TG -taping group, n=15 and CG - control group, n=15). Dominant side ankles of all subjects in TG were taped by closed basketweave technique before exercise. For exercise stimulation, 10, 20, 30 and 40 minutes of running exercise was carried out on the treadmill (10km/h, 0%) with 48 hours intervals. Cybex 770 Model(Lumex, U.S.A) was used to measure isokinetic muscle strengths at 30°/sec and 120°/sec angular velocity, and then peak torque % body weight and average power % body weight were collected to analyze. To measure proprioceptive function, hop test and Romberg test were conducted. To analyze the datas, repeated measured two way ANCOVA and T-test were used and significance was set at p<.05 for all tests. The results are as follows; 1) Isokinetic muscle strengths of plantar flexor were significantly decreased by taping(p<.01). 2) Power of dorsi flexor, plantar flexor and eversor were significantly decreased by taping(p<.05). 3) The distance of hop test after exercise were significantly increased compared to before exercise in TG, and the distance of hop test at 20 min after exercise were significantly increased compared to before exercise in CG. 4) The duration of Romberg test of all measurements were significantly decreased in TG compared to CG. The duration of Romberg test at 10 min after exercise were significantly increased compared to before exercise and then significantly decreased at 20 min after exercise and these at 10 min after exercise were significantly increased compared to 20 and 30 min after exercise in TG. In conclusion, taping on ankle can have an negative effect on ankle muscle strength, power, proprioceptive function and when baseball players need taping, exercise duration should be considered.