Gastric carcinoma is derived from epithelial cells in the gastric mucosa. We reported an extremely rare case of submucosal gastric carcinoma originating from the heterotopic submucosal gastric gland(HSG) that was safely diagnosed by laparoscopy and endoscopy cooperative surgery(LECS). A 66-year-old man underwent gastrointestinal endoscopy, which detected a submucosal tumor(SMT) of 1.5 cm in diameter on the lesser-anterior wall of the upper gastric body. The tumor could not be diagnosed histologically, even by endoscopic ultrasound-guided fine-needle aspiration biopsy. Local resection by LECS was performed to confirm a diagnosis. Pathologically, the tumor was an intra-submucosal well differentiated adenocarcinoma invading 5000 μm intothe submucosal layer. The resected tumor had negative lateral and vertical margins. Based on the Japanese treatment guidelines, additional laparoscopic proximal gastrectomy was curatively performed. LECS is a less invasive and safer approach for the diagnosis of SMT, even in submucosal gastric carcinoma originating from the HSG. Gastric carcinoma is derived from epithelial cells in the gastric mucosa. We reported an extremely rare case of submucosal gastric carcinoma originating from the heterotopic submucosal gastric gland (HSG) that was safely diagnosed by laparoscopy and endoscopy cooperative surgery (LECS). A 66-year -old man underwent gastrointestinal endoscopy, which detected a submucosal tumor (SMT) of 1.5 cm in diameter on the lesser-anterior wall of the upper gastric body. The tumor could not be diagnosed histologically, even by endoscopic ultrasound-guided fine-needle aspiration Biopsy. Local resection by LECS was performed to confirm a diagnosis. Pathologically, the tumor was an intra-submucosal well differentiated adenocarcinoma invading 5000 μm intothe submucosal layer. The resected tumor had negative lateral and vertical margins. Based on the Japanese treatment guidelines, additional laparoscopic proximal gastrectomy was curatively performed. LECS is a less invasive and safer approach for the diagno sis of SMT, even in submucosal gastric carcinoma originating from the HSG.