The development of colorectal cancer has been known as the adenoma-carcinoma sequence. Yet another route for cancer development has recently been proposed, which is call the de novo pathway based on the reports of the depressed-type early colorectal cancers. Early colorectal cancer is defined as invasive tumor limited to the colorectal mucosa or submucosa, regardless of the presence or absence of lymph node metastasis. Especially, depressed type colorectal cancers have a much higher rate of submucosal invasion and rapid progression despite of their relatively small sizes. Our case displayed a depressed type tumor that was only 5mm in diameter and it had invaded the deep submucosal layer (SM3); this was resected by operation with no predictive endoscopic finding. So, the depressed type tumor can show deep invasion or lymph node metastasis despite of its small size.