Some patients with hip osteoarthritis report that urinary incontinence (UI) is improved following total hip arthroplasty (THA). However, the type and severity of UI remain unclear. In this study, we hypothesize that both stress urinary incontinence (SUI) and urge urinary incontinence (UUI) are improved after THA. We assess the characteristics of UI and discuss the anatomical factors related to UI and THA for improved treatment outcome. Fifty patients with UI who underwent direct anterior-approach THA were evaluated. Type of UI was assessed using four questionnaires: Core Lower Urinary Tract Symptom Score (CLSS), Urogenital Distress Inventory Short Form (UDI-6), International Prostate Symptom Score (IPSS), and Overactive Bladder Symptom Score (OABSS). Uroflowmetry and postvoid residual urine were measured using ultrasound technology. Hip-joint function was evaluated using Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and range of motion (ROM). Of the 50 patients, 21 had SUI, 16 had mixed urinary incontinence (MUI), and eight had urgency urinary incontinence (UUI). In total, 36 patients were better than improved (72 %). The rate of cured and improved was 76 % for SUI, 100 % MUI, and 50 % UUI. The improvement of ROM was more significant in cured or improved patients than in stable or worse patients. Improvement in mild UI may be an added benefit for those undergoing THA for hip-joint disorders. These data suggest that for patients with hip-joint disorder, hip-joint treatment could prove to also be a useful treatment for UI.