A 48-year-old man was referred to our institute for the evaluation of a concomitant gastric submucosal tumor and right adrenal tumor, incidentally found by ultrasound examination. Computed tomography showed a mass with a diameter of 6 cm adjacent to the stomach and the right adrenal tumor with a diameter of 3 cm. These tumors had similar characteristics in both plain and enhanced imagings. By magnetic resonance imaging, the intensity of the right adrenal tumor was equivalent to the liver in both T1 and T2 weighted images. On the other hand, the gastric submucosal tumor showed low intensity in T1 weighted images and high intensity in T2 weighted images. An adosterol scintigram showed slight accumulation at the region of adrenal tumor. The results of all conducted serum and urinary hormonal examinations were found to be within the normal range. Adrenalectomy and partial gastrectomy were performed laparoscopically. Pathological diagnosis of the adrenal tumor was a cortical adenoma, and that of the gastric submucosal tumor was gastrointestinal stromal tumor (GIST). The gastric tumor was immunohistochemically stained positive with the C-kit and CD34 and negative for s-100 protein and desmin. Histopathological diagnosis was coincident with gastric GIST and right adrenocortical adenoma, and the GIST was diagnosed as a high risk tumor because its diameter was over 5 cm.