Adenosquamous carcinoma of the pancreas is a rare tumor, which is difficult to diagnose. A 65-year-old man was admitted complaining of abdominal pain. Abdominal computed tomography (CT) demonstrated a cystic mass in the pancreatic body. Endoscopic ultrasound (EUS) showed an approximate 1.0 cm-sized hypoechoic cystic mass with a solid portion in the pancreatic body and narrowing of the main pancreatic duct. Under the impression of acute pancreatitis with a pseudocyst diagnosis, medical therapy including pancreatic stent insertion was administered to the patient for 4 weeks. A distal pancreatectomy was performed with the suspicion of pancreatic cancer due to the remaining mass on a follow-up CT scan, and the tumor was histopathologically diagnosed as stage I (TNM classification) adenosquamous carcinoma of the pancreatic body. The patient was discharged without any problems and has been on follow-up without recurrence. We report a case of adenosquamous carcinoma of the pancreas that was diagnosed relatively early with the help of EUS.