Purpose The aim of this study was to determine of validity of thoracic kyphosis and pelvic tilt using smartphone application in chronic stroke patients. Methods Subjects were stroke patients (n=15) and healthy controls (n=15). The minimal detectable change (MDC) and standard error of measurement (SEM) were estimated to determine a real change for thoracic kyphosis and pelvic tilt angle. Correlation was analyzed to explore the relationships between smartphone application and inclinometer. Results The thoracic kyphosis and pelvic tilt angle had an SEM of 1.88, 1.10, MDC of 3.68, 2.17. The high correlation was observed between the measured with the inclinometer data and the measured by the smartphone application data (thoracic kyphosis, r=0.93, p<0.001; pelvic tilt r=0.93, p<0.001). Conclusion Our experimental results indicate that smartphone application was appropriate to measure thoracic kyphosis and pelvic tilt angle in stroke patients.