This study was conducted to investigate the characteristics of smartphone usage and posture of users during using smartphone. A survey was conducted for 983 smartphone users to understand the association between smartphone usage and including subjective symptoms associated with musculoskeletal disorders. Main results from the survey were as follows; 1) 18.8% of the subjects experienced musculoskeletal symptoms at least at one of body parts. Specifically, 8.1%, 5.6%, 4.1%, and 11.3% of the subjects experienced musculoskeletal symptoms at neck, shoulder, elbow, and hand respectively, 2) The symptoms of musculoskeletal disorders were also associated with amount of text message and time for daily usage of smartphone. Specifically, relative risks of musculoskeletal disorders at hand/wrist/fingers in terms of "amount of text message" and "time for daily usage" for experienced user were 1.425 and 1.368 respectively to inexperienced user. This study identified 'amount of text message' and 'time for daily usage' as the major risk factors of smartphone usage in terms of musculoskeletal symptoms. The results of the study provided a good basis in order to remove or reduce the risks associated with musculoskeletal symptoms due to smartphone usage.