A rectocele with a weakened rectovaginal septum can be repaired with various surgical techniques. We performed laparoscopic posterior vaginal wall repair and rectovaginal septal reinforcement without mesh using a modified transperineal approach. A 63-year-old woman with outlet dysfunction constipation complained of lower pelvic pressure and sense of heaviness for 30 years. Initial defecography showed an anterior rectocele with a 45-mm anterior bulge and perineal descent. Laparoscopic procedures included peritoneal and rectovaginal septal dissection directed toward the perineal body, rectovaginal septal suturing, and peritoneal closure. The patient started a soft diet the following day and was discharged on the 5th postoperative day without any complications. The patient had no dyschezia or dyspareunia, and no problem with bowel function; 3-month follow-up defecography showed a decrease in bulging to 18 mm. Laparoscopic posterior vaginal wall and rectovaginal septal repair is safe and feasible for treatment of a rectocele, and enables early recovery.