The present study aimed to clarify the effects of "shoe-lacing tightness" on gait. Participants The present study aimed to clarify the effects of "shoe-lacing tightness" on gait. Participants included nine males (22.8±1.2 years) and nine females (21.9±1.8 years) , who walked at their normal included nine males (22.8±1.2 years) and nine females (21.9±1.8 years) , who walked at their normal pace and a fast pace under two shoe-lacing conditions, which differed in lacing tightness (fit and loose) . pace and a fast pace under two shoe-lacing conditions, which differed in lacing tightness (fit and loose) . Walking speed, step length, and step width were measured with a walking posture measurement system, Walking speed, step length, and step width were measured with a walking posture measurement system, which includes Kinect v2. Gait cycle time, trunk movement, and Harmonic Ratio (HR) were measured which includes Kinect v2. Gait cycle time, trunk movement, and Harmonic Ratio (HR) were measured and calculated with another system, which uses two inertial sensors placed on the thoracic vertebrae and calculated with another system, which uses two inertial sensors placed on the thoracic vertebrae (Th6) and sacrum (S2) of each participant. Two-way repeated-measures MANOVA was conducted (Th6) and sacrum (S2) of each participant. Two-way repeated-measures MANOVA was conducted for all analysis items, and significant differences were found in the walking task and the shoe-lacing for all analysis items, and significant differences were found in the walking task and the shoe-lacing condition. Walking speed, vertical movement of S2, and vertical HR of Th6 under loose-lacing conditions condition. Walking speed, vertical movement of S2, and vertical HR of Th6 under loose-lacing conditions were significantly smaller than those under fit-lacing conditions. Mediolateral movement of Th6 and were significantly smaller than those under fit-lacing conditions. Mediolateral movement of Th6 and anteroposterior movement of S2 under loose-lacing conditions were significantly larger than those under anteroposterior movement of S2 under loose-lacing conditions were significantly larger than those under fit-lacing conditions. This study clarified that loose-lacing conditions affects gait. fit-lacing conditions. This study clarified that loose-lacing conditions affects gait.