A woman in her 30s was diagnosed with ulcerative colitis (UC) 4 years ago and treated with tacrolimus, azathioprine, and prednisolone 5mg (PSL). Skin ulcers appeared on the right lower leg during the course of treatment, diagnosed as pyoderma gangrenosum (PG). The patient initially improved with an increased PSL and infliximab dose, but then developed multiple skin ulcers and folliculitis throughout her body. She was transferred to our hospital for PG exacerbation treatment. She developed fever after transfer and contrast-enhanced computed tomography showed multiple abscesses in the lungs and kidneys. PSL was decreased and infliximab was discontinued. Antibiotic therapy and granulocyte/monocyte apheresis (GMA) were started. Fever persisted even after antibiotic treatment, and her general condition did not improve. A right renal abscess puncture was performed. Pus was sterile. A sterile abscess associated with PG was suspected. The PSL dose was increased to 1mg/kg and infliximab restarted. Thereafter, the patient's general condition improved, and both lung and renal abscesses contracted. Skin ulcer epithelialization was also observed. Abdominal symptoms were mild during the course of the disease, and colonoscopy showed only a localized ulcerative lesion in the rectum. The patient was later transferred to the department of dermatology at our hospital for PG treatment. Aseptic abscesses are caused by neutrophil infiltration without infection and have been reported to be associated with neutrophilic dermatosis and inflammatory bowel disease. UC-associated aseptic abscess is rare. This is only the sixth case in Japan. Aseptic abscesses can occur in various sites, including subcutaneous and deep organs, but this is the first kidney abscess case. In previous reports, PSL, infliximab, colchicine, and infliximab+GMA were used for aseptic abscesses associated with UC. They all showed abscess reduction. Aseptic abscesses associated with PG should be considered if abscess lesions occur during the course of UC, and a treatment strategy including enhanced immunosuppression should be considered.