Generally, conservative treatment is performed at the initial stage of Osgood-Schlatter disease (OSD) to decrease pain. When this conservative treatment is no longer effective, surgery will be performed to decrease OSD pain by removing a tibial tuberosity avulsed bone and a synovial capsule. We reported a time-series change of pain before and after the OSD surgery on a wrestling athlete. The present subject was a 20-year-old male wrestler (height 183 cm ; weight 90 kg), who received OSD surgery on the left knee. Numerical rating scale (NRS) was used to determine pain before and after the OSD surgery. NRS was measured by three positions : resting position (RP), sitting with knee extending position (SKEP), squat with knee flexing 90° position (SK 90 P) and pressure pain (PP). Immediately after the OSD surgery, NRS at the RP, SKEP, SK 90 P, and PP decreased from NRS 3 to NRS 0, NRS 5 to NRS 1, NRS 8 to NRS 6, and NRS 8 to NRS 1, respectively. Three weeks after the OSD surgery, pain at the SKEP and PP decreased to NRS 0. Eight and eleven weeks after the OSD surgery, pain at the SK 90 P decreased to NRS 2 and NRS 1, respectively. The present case study suggests that OSD surgery may progressively decrease pain. Further studies are needed to clarify the effect of OSD surgery on pain.