A 74-year-old man with nausea underwent upper gastrointestinal endoscopy, and a 0-IIb type tumor was found in the middle thoracic esophagus. Histological examination with endoscopic biopsies revealed squamous cell carcinoma (SCC), and chromoendoscopy with iodine staining revealed that the superficial SCC involved nearly the entire circumference of the esophageal lumen. There were neither nodal nor distant metastases. Complete circular endoscopic submucosal dissection (ESD) was successfully achieved with tumor-free margins in an en bloc fashion. The histopathological examination confirmed a diagnosis of intramucosal invasive carcinoma limited to the lamina propria mucosae without angiolymphatic invasion. Oral prednisolone was started with 0.5 mg/kg daily on the 3rd post-ESD day, tapered gradually, and then discontinued 8 weeks later without adverse effects. There were no complaints of dysphagia following ESD. On follow-up endoscopy with iodine staining, which was scheduled at 1, 3 and 6 months after ESD, there was no postprocedural esophageal stricture, and neither recurrent nor metachronous lesions were found. Thus, the patient required no sessions of endoscopic balloon dilatation. At the last outpatient clinic visit 7 months after ESD, he remained well without dysphagia. Oral prednisolone administration may offer an effective therapeutic strategy to prevent the post-ESD esophageal stricture after complete circular ESD.