Stress fractures of the upper limbs are uncommon, and are most often reported as individual cases or small series. In particularly, stress fractures around the wrist are even less common. A stress fracture of the radial styloid process in a judo player was surgically treated, and a favorable treatment outcome was obtained. A 16-year-old adolescent boy experienced pain in the right wrist, with no apparent trigger, while playing judo. Stress fracture of the radial styloid process was diagnosed with plain radiographs and was treated conservatively with cast immobilization. Although bone union was achieved, the fracture recurred after he resumed paying judo. Thus, surgical treatment was performed. The procedure was resection of the distal bone fragment. He resumed practicing 2 months postoperatively and returned to judo matches after 1 more month. As of 1 year after distal bone fragment resection, he was able to participate in judo without pain, limited range of motion, or instability of the wrist.