Background: Gastric tube carcinoma (GTC) after esophagectomy has been observed increasingly in recent years after advanced treatment of esophageal carcinoma. Surgical removal of the reconstructed gastric tube is not usually preferred; however, endoscopic submucosal dissection (ESD) is greatly anticipated to be a promising option. This study investigated the efficacy and safety of ESD for GTC. Methods: This study was designed based on a retrospective survey performed at our single center between 2003 and 2018. Patients with GTC were treated with ESD and followed-up according to the policy of our institution. The curability of ESD was evaluated histologically according to the Japanese gastric cancer treatment guidelines. Patient characteristics, outcomes of ESD procedures, and long-term outcomes were analyzed. Results: A total of 31 patients (2 females; median age, 73 years) with 45 GTC cases were treated with ESD. The mean period from esophagectomy to the diagnosis of GTC was 10.6 years. The only adverse event due to ESD was bleeding (2 patients: 6.5%). No fatal events, such as perforation, occurred. The rates of complete resections and curative resections were 80.6% and 48.4%, respectively. The 3-year and 5-year overall survival rates were 67.6% and 47.7%, respectively. The 3-year and 5-year disease-specific survival rates were 100% and 92.9%, respectively. One patient died of GTC and 14 patients died of other diseases, including five primary carcinomas. Conclusions: ESD for GTC can be a safe treatment and contribute to positive long-term outcomes. Long-term regular gastroscopy is required for early detection. Moreover, additional care should be given to GTC patients who are at high risk for other primary carcinomas or comorbidities.