Adenosquamous carcinoma (ASC) is characterized as a mixed neoplasia (adenocarcinoma with glandular architecture and squamous cell carcinoma [SqCC]). Because most ASCs are found in the advanced stage at the time of diagnosis, early gastric ASC is an extremely rare tumor. Here, we present the case of an incidental finding of early gastric ASC in a 61-year-old Korean man during a health screening. Histological biopsy through esophagogastroduodenoscopy revealed a moderately differentiated adenocarcinoma in the distal body. The patient underwent endoscopic submucosal dissection and was diagnosed with ASC. The SqCC components of this tumor were located adjacent to the adenocarcinoma components and occupied 40% of the tumor. Two individual tumor components had invaded into the submucosal layer with lymphovascular invasion. An abdominal computed tomography scan indicated no definite mass or wall thickening of the stomach and revealed neither lymph node enlargement nor distant metastasis. To the best of our knowledge, this is the 14th reported case of early gastric ASC, and all cases were reported in East Asians.