A 54-year-old obese man (Class 2 obesity). Right diaphragmatic eventration was demonstrated on medical examination for five years. The patient visited our hospital with a chief complaint of dyspnea. Thoracoabdominal computed tomography (CT) revealed prolapse of the small intestine, transverse colon, and greater omentum in the right thoracic cavity, and the patient was diagnosed with diaphragmatic hernia. After contrast-enhanced CT examination, the patient developed a cough attack and respiratory failure. During hospitalization, the patient received mechanical ventilation management ; however, his respiratory condition did not improve, and he underwent surgery. Upon thoracotomy, a defect of approximately 10 cm was observed in the center of the right diaphragmatic tendon, and the prolapsed organs were the right lobe of the liver, gallbladder, small intestine, transverse colon, and greater omentum. Since a large number of organs were prolapsed, the volume was reduced by omentectomy and cholecystectomy. The prolapsed organs were then repositioned, and the mesh was fixed over the hernia orifice to complete the surgery. No recurrence was observed for three years after the surgery. Here, we report a surgical case of adult idiopathic diaphragmatic hernia that led to respiratory failure and required mechanical ventilation management.