<Abstract>A 70-year-old man underwent total gastrectomy and splenectomy for gastric cancer. On the second post-operative day, swelling with redness was noted at the site of drain insertion. The site of redness expanded rapidly and the patient developed purpura with blood blisters complicated by concomitant shock, respiratory failure, and disseminated intravascular coagulation (DIC), leading to a sudden worsening of his general condition. He was diagnosed with a necrotizing soft tissue infection. A drain was inserted through the superficial fascia to initiate irrigation drainage. Aeromonas hydrophila was detected in the subcutaneous effusion and blood cultures. The drainage region was enlarged as needed based on the amount of necrosis. Debridement was performed after his general condition had stabilized. Ninety-two days postoperation, he was transferred to another hospital for skin grafting. Necrotizing soft tissue infections due to A. hydrophila usually have a life-threatening course. However, irrigation drainage through the superficial fascia might be effective when extensive debridement cannot be provided immediately because of a bleeding tendency due to shock or DIC.