A 68-year-old man who presented to the emergency room with complaints of fever and right lower quadrant abdominal pain was diagnosed with ascending colon diverticulitis. Two days later, he came to our department with increasing right groin pain and swelling. On examination, we identified a painful mass in the right groin that was irreducible and erythematous. The laboratory data revealed leukocytosis and high C-reactive protein level. Enhanced abdominal computed tomography showed a suspicion of intestinal prolapse in the right groin. A diagnosis of right incarcerated inguinal hernia was made and emergency surgery was performed. On diagnostic laparoscopy, we identified a small hernia orifice in the right femoral area, but no abdominal organ was prolapsed. A small amount of turbid fluid was drained from the femoral hernia orifice. We performed high ligation of the hernia sac, and repaired the hernia with a mesh plug via the anterior approach. A thickened peritoneal membrane with inflammation and neutrophil infiltration was observed on pathological examination ; thus, we diagnosed a femoral hernia abscess caused by ascending colon diverticulitis.