Abdominal computed tomography of a 71-year-old man revealed a 3-cm mass in gastric cardia. Although the mass was widely attached to the gastric wall, no clear contrast enhancement was observed. Abdominal magnetic resonance imaging revealed the mass to have homogenous high intensity on T2W1 images and isointensity on T1W1 images. On diffusion-weighted imaging, no high intensity was observed. However, the mass had a smooth surface and was widely attached to the gastric wall, consistent with computed tomography findings. A gastric submucosal tumor was suspected. Laparoscopic tumor resection was performed. Histopathologic diagnosis of the mass was a bronchogenic cyst derived from the respiratory primordium originating in the foregut of the primitive intestine. Such cysts are mostly found in the mediastinum or thoracic cavity; their occurrence on the gastric wall is extremely rare. Despite this, we think that bronchogenic cysts should be considered in the differential diagnosis of abdominal unilocular cystic diseases.