In this paper, we report an extremely rare case of an abscess that developed in the inguinal hernial sac after surgery for peritonitis. A 60-year-old man underwent laparoscopic low anterior resection for rectal cancer. One day after this operation, peritoneal drainage and ileostomy were performed for rectal anastomotic leakage. Five days after the second operation, computed tomography revealed an abscess in the left inguinal hernial sac. Subsequently, hernioplasty and resection of the inflamed sac were performed.