In general, femur fractures in the younger patient population are the result of high energy trauma, such as motorcycle accidents or traffic accidents. A 43-year-old healthy man presented with painful swelling of his right thigh. Plane radiographs showed short oblique fracture of the femur shaft with comminution. He had no medical history such as osteoporosis or any metabolic bone disorder. He was a healthy man with no smoking and no alcohol drinking, enjoying sports activity such as baseball and football. He was injured during defense time of a baseball game by rapid turning motion to catch a ball. We performed intramedullary interlocking nailing for the femur shaft fracture and the fracture was uneventually healed with no complication. To our knowledge, femur shaft fracture which occurred during playing baseball in a healthy middle-aged man has not been reported in our country. So we report this case with a review of the literature.