Objective. Measurements of knee joint movement in gait analysis may result in large errors caused by misplacement of reflective markers by the testers. To properly understand the measurement results, it is important to guarantee the reliability of the measurement method used for the purpose. The aim of this study was to confirm the interrater reproducibility of a measurement method with a rigid marker set (RMS). Methods. The study subjects were four healthy adults, and the testers were three physical therapists. The interrater reproducibility of the measurements was verified by using the coefficient of multiple correlations (CMCs) and the standard error of measurement (SEM). Results. The average CMCs values of 4 subjects in knee joint movement at the stance phase were greater than 0.8, and the average SEM values of 4 subjects in knee joint movement at the stance phase were also relatively good (maximum error: 2.42°). Conclusion. Based on these results, the measurement method with estimation of anatomical landmarks using the RMS can prevent misplacement during attachment of the reflective markers, as long as the testers have sufficient experience in attaching reflective markers.