Intraperitoneal cyst occurring in the lesser omentum is extremely rare entity. Because of the absence of abdominal symptoms, omental cyst is occasionally found accidentally in imaging examination performed during health screening. We experienced a case of cystic lymphangioma that occurred in the lesser omentum, which was successfully resected under complete laparoscopic procedure. A 50-year-old Japanese woman was admitted to our hospital because a cystic mass was found in the abdomen. Abdominal computed tomography scan was performed because she had a traffic accident, despite complaining no abdominal symptoms. The abdominal computed tomography scan and magnetic resonance imaging revealed a large cystic mass in the lesser omentum adjacent to the lesser curvature of the stomach, which was resected with a complete laparoscopic procedure. As the cystic wall was closely attached to the lesser curvature of the gastric wall, an ultrasonic coagulating shear was quite helpful to entirely mobilize the cyst from the surrounding structure such as lesser curvature of the stomach. After placing clips to the feeding vessels to the cyst branched from the accessory hepatic vessels, the entire cyst was mobilized without leakage of cystic content. The postoperative course was uneventful with slight delayed gastric emptying due to partial denervation of the lesser curvature of the stomach. The patient was discharged on eighth day after surgery without any postoperative complications. This is the first case of cyst of lesser omentum resected under complete laparoscopic procedure and certainly highlights advantage and feasibility of laparoscopic approach for cases with abdominal cystic lesions. Laparoscopic excision of cystic lymphangioma in the lesser omentum provides all the advantage of minimally invasive procedure.