For existing measurements of the hip range of motion (ROM), marker-based motion capture systems (MBSs) are utilized as a gold standard, even though they have disadvantages such as high cost and inconvenience due to the need for marker attachment. To address these limitations, a novel markerless motion capture system (MLS) is suggested. An MLS might be affected by environmental and physical factors; however, no existing research has been conducted on the relationship between the validity of MLSs and individual physical characteristics including height, leg length, knee width, and body mass index (BMI). The purpose of this study was to confirm the overall validity of MLSs in estimating hip joints and the correlation between the validity and physical characteristics. Hip angles were collected using an MBS and an MLS during single-joint motions. Intraclass correlation coefficient (ICC; 3,1) analysis demonstrated a high validity (0.870–0.996) of the MLS. Groups classified by height, leg length, and BMI showed clinical differences (thresholds: 2–5°) in root mean square error (RMSE). Height and leg length showed a negative correlation with the RMSE in a Spearman analysis. From the results of this study, we confirmed that the novel MLS is highly promising for measuring the hip ROM, although the validity of MLSs could be affected to some extent by physical characteristics.