We report a case in which the combination of an interparietal inguinal hernia and ipsilateral ectopic testicle mimicked a spigelian hernia. The patient was a 22-day-old boy who presented with a reducible mass that extended from the right lumbar region to the iliac fossa region. The right testis was palpable in the right lumbar region. Ultrasonography and magnetic resonance imaging revealed that a small bowel had herniated through the inguinal region below the external oblique aponeurosis. Surgery was performed when the patient was 23 months old. Laparoscopic examination to identify the hernia orifice revealed that it was the deep inguinal ring, and the testicular vessels and the vas deferens passed beneath the hernia sac. An inguinal incision was made, and a hernia sac was observed passing through the deep inguinal ring and extending superiorly below the aponeurosis. The testis was found in the hernia sac. Traditional inguinal herniorrhaphy and traditional orchidopexy were performed, and the postoperative course was uneventful. It is difficult to understand the surgical anatomy of interparietal hernias, but once the surgical anatomy is understood, surgical repair is simple. We report the case with a review of the literature and also emphasize that laparoscopic exploration is helpful during surgery.