Inertial measurement unit systems are wearable sensors that can measure the movement of a human in real-time with relatively little space and high portability. The purpose of this study was to investigate the accuracy of the inertial measurement unit (IMU) system for gait analysis by comparing it with measurements obtained using an optical motion capture (OMC) system. To compare the accuracies of these two different motion capture systems, the Spatio-temporal and kinematic parameters were measured in young adults during normal walking. Thirty healthy participants participated in the study. Data were collected while walking 5 strides on a 7 m walkway at a self-selected speed. Results of gait analysis showed that the Spatio-temporal (stride time, stride length, cadence, step length) and kinematic (knee joint peak to peak of movement) parameters were not significantly different in the participant. Spatio-temporal and kinematic parameters of the two systems were compared using the Bland-Altman method. The results obtained showed that the measurements of Spatio-temporal and kinematic parameters of gait by the two systems were similar, which suggested that IMU and OMC systems could be used interchangeably for gait measurements. Therefore, gait analysis performed using the wearable IMU system might efficiently provide gait measurements and enable accurate analysis. (OMC) system, which utilizes multiple optical cameras to calculate 3D positions of body joints, is most commonly used to analyze gait phases and has the advantage of providing real-time measures of movement a rapid reaction rate and the ability to measure data close to the human movements even for complex motions [7,9].Over the past few years, a number of wearable inertial measurement unit (IMU) systems have been used to analyze human joint movement in laboratories or in living environments [10]. The IMU system is useful because the system function is verified in the gait analysis of people with disabilities in low cost and non-invasive methods [11][12][13]. In order to increase the universal use of the IMU system, it is very necessary to analyze the accuracy of the IMU system by comparing the results of the gait analysis of the IMU system and the OMC system. Inertial measurement unit systems use accelerometers, gyroscopes, and magnetometers to provide data on the motion characteristics of joints and segments during various tasks [10]. IMU system can measure human joint movements in real-time and has the advantage of being able to measure in relatively little space and is highly portable compared to the OMC system. However, the disadvantage of the IMU system is that it includes a position drift that may vary over time with lower position accuracy. Position accuracy is a problem because it is determined by constantly integrating acceleration over time to calculate speeds and positions, and this results in cumulative measurement errors. In addition, since the position of the IMU sensors for measuring joint movement does not match the anatomical position of the ...