A man in his 80s was referred to our hospital with the chief complaint of perianal erosion. Colonoscopy revealed a peripheral flat lesion in the anal canal. Since immunohistological examination showed positive for CK20 and negative for GCDFP15, we made a preoperative diagnosis of anal canal cancer with Pagetoid spread. It was diagnosed as cT1bN0M0, cStage Ⅰ by TNM classification, and laparoscopic abdominoperineal resection with TpTME was performed. Negative biopsy of the perianal skin was confirmed both preoperation and during the operation. The postoperative course was uneventful, and no urinary dysfunction was observed. The patient was discharged 15 days after the operation. The histopathological diagnosis was negative margin. The patient is alive without recurrence 1 year after the operation. Adenocarcinoma of anal canal with Pagetoid spread is rare, and differentiation from Paget's disease is important for determining treatment policy. By conducting a detailed examination of the extent of tumor progression and using TpTME together, it was possible to perform surgery that both secured the CRM and preserved urinary function.