Endoscopic mucosal resection (EMR) is one of the main treatment modalities for broad-based protruded-type or flat-type lesions of colorectal tumors. In this report, the procedures and skills required for EMR, which forms the basis of colonoscopic treatment, are described based on the current situation. The knack of EMR is to understand the characteristics and selection of an adequate snare in each situation, selection of adequate local injection drug, to learn techniques of local injection, to master skilful snaring techniques, to estimate the degree of radial cure of locally resected regions using magnifying observation and the practice of additional trimming. As a result of the practice and learning of these points, EMR, including piecemeal resection, can be enough for curative treatment of colorectal tumor. We can and should differentiate EMR from endoscopic submucosal dissection (ESD) for various types of colorectal tumor according to detailed endoscopic diagnosis using magnification prior to treatment.