Purpose <p>The purpose of the present study was to quantitatively assess the characteristics of lumbar spine motor function in patients with lumbar spinal stenosis (LSS) who experienced falls and to determine the association between falls and lumbar spine motion.</p> Methods <p>This cross-sectional study enrolled consecutive patients with clinically and radiologically defined LSS indicated for surgical treatment at a single center. The lumbar motion task consisted of bending forward to the maximum range of motion of the lumbar spine in the standing position, followed by a return to the upright position. The occurrence of falls in the past year was recorded. Binomial logistic regression analysis was performed to evaluate the association between falls and lumbar spine motion while using basic characteristics, general fall risk assessment, and known fall-related factors in patients with LSS as adjustment variables.</p> Results <p>A total of 102 participants were analyzed; 43 participants had a history of falls. Binomial logistic regression analysis showed that delayed lumbar spine motion was significantly associated with the occurrence of falls (odds ratio, 2.56; 95% confidence interval, 1.09–6.03).</p> Conclusion <p>The results of this study suggest that delayed lumbar motion is an important factor associated with falls in patients with LSS.</p>