Electron microscopic findings obtained from seven scirrhous carcinomas of the stomach were analyzed dividing each carcinoma into superficial, deep, and peripheral parts. Proliferation of collagen fibrils, disappearance of plasma membranes, and extracellular release of cell organellae of cancer cells were considered to be peculiar findings to this type of cancer. These phenomena were observed frequently at the deep part of the cancer, but rarely at the peripheral and superficial parts. Replacement of damaged cells by the proliferated collagen fibrils at the central area of the cancer and disconnection of cancer cells from scirrhous lesion at the peripheral part were considered to contribute to the biological behaviour of this carcinoma.