A 37-year-old female was scheduled for minimally invasive mitral valve replacement and Maze operation using the robotically controlled camera (AESOP 3000, Computermotion^®, USA). Thoracic incision and carbon dioxide insufflation was started. The end tidal carbon dioxide suddenly decreased with hypotension and an increase in central venous pressure to 70 mmHg. Then, cardiopulmonary bypass was started and large amount of gas was aspirated. Carbon dioxide embolism was suspected, carbon dioxide insufflation was discontinued. The aspiration of carbon dioxide embolus from cannulae for cardiopulmonary bypass confirmed our diagnosis. The gas flowed out from the peritoneal cavity following diaphragmatic incision, we suspected that the insufflating needle was placed into peritoneal cavity. The operation was completed uneventfully. No neurologic and cardiopulmonary sequelae were noted. We experienced a case of carbon dioxide embolism incidentally induced by carbon dioxide insufflation into closed intraperitoneal cavity.