[Objective] The objective of this study was to investigate the reliability of smartphone-based measurements of the upper body, thigh, and shin segmental angles, and the hip and knee joint angles when walking. [Method] The sample size of this study included eight young and healthy college students. In this study, smartphones were used to determine the changes in angles when the subjects walked with smartphones attached to their torso (upper body), thigh, and shin. The obtained angles represented segmental angles for the torso, thigh, and shin, and were later used to calculate hip and knee joint angles. Measurements were taken and then the test-retest method was used to evaluate the agreement between the test and retest results. [Results] According to the results, a very high reliability for the torso and shin segmental angles (ICC>0.75) and a high reliability for the thigh segmental angle and hip and knee joint angles (ICC>0.60) were displayed. [Conclusion] According to the results of this study, it was established that smartphones can be sufficiently used as devices for gait analysis.