A 34-year-old woman presented with a complaint of swelling of the buttock. A physical examination indicated a subcutaneous soft elastic tumor. CT and MRI showed a 6-cm subcutaneous dumbbell-shaped cystic tumor in the buttock, extending into the pelvic cavity. Laparoscopic resection with a transsacral approach was performed without an accurate preoperative diagnosis. Laparoscopically we found a subcutaneous tumor in the buttock penetrating into the pelvic cavity on the dorsal side of the mesorectum, through the gap of the levator ani muscle around the coccygeal bone. The cystic tumor and coccygeal bone were totally resected. Pathological findings of the specimen revealed a cyst wall composed of squamous epithelium that contained atheromatous contents. The lesion was diagnosed as an epidermal cyst. The patient was discharged from hospital on the eighth postoperative day without any complications. There has been no recurrence of symptoms after surgery. An epidermal cyst is a benign tumor that is commonly experienced in daily medical practice. Malignant transformation of epidermal cysts are reported on rare occasions, and total resection of the tumor is recommended. This case shows that transsacral resection with laparoscopic surgery for cystic tumors extending from the buttocks into the pelvic cavity is a safe and appropriate surgical approach.