The use of electronic patient-reported outcomes has increased recently, and smartphones offer distinct advantages over other devices. However, previous systematic reviews have not investigated the reliability of the Center for Epidemiologic Studies Depression Scale (CES-D), Generalized Anxiety Disorder-7 (GAD-7), and Kessler Screening Scale for Psychological Distress (K6) when used with smartphones, and this has not been fully explored. This study aimed to evaluate the equivalence of the paper and smartphone versions of the CES-D, GAD-7, and K6, which were compared following a randomized crossover design method in 100 adults in Gunma, Japan. Participants responded to the paper and smartphone versions at 1-week intervals. The equivalence of paper and smartphone versions was evaluated using the intraclass correlation coefficient (ICC agreement ). The mean participant age was 19.86 years (SD = 1.08, 23% male). The ICC agreements for the paper and smartphone versions of the CES-D, GAD-7, and K6 were 0.76 (95% confidence interval [CI] 0.66-0.83), 0.68 (95% CI 0.59-0.77), and 0.83 (95% CI 0.75-0.88), respectively. Thus, the CES-D and K6 scales are appropriate for use in a smartphone version, which could be applied to clinical and research settings in which the paper or smartphone versions could be used as needed.