The purpose of this study was to investigate the acceleration characteristics of Taekwondo Keumgang Poomsae in terms of Inertial Measurement Unit (IMU) sensor and to compare temporal consistency, as a performance parameter, between elite Poomsae athletes (PA) and elite demonstration athletes (DA) in attempt to see performance difference. Five PA and five DA voluntarily participated in this study. They performed Keumgang Poomase twice after having a 5-min resting interval and IMU sensor measured linear accelerations of Poomsae motions. The resultant acceleration consisting of tri-axial accelerations were calculated. The major events, defined as peak moments of the resultant acceleration of the wrist, were used for correlation analysis. Results indicated the temporal consistencies of PA were 0.9989 to 0.9999 and those of DA were 0.9970 to 0.9989. There was no statistical difference on mean values between two groups. From the perspective of mean standard deviation (SD) at each event, the SD suddenly increased every time after Hakdariseogi. The IMU sensor would be a good measuring tool for temporal performance of Taekwondo Poomsae.