A cutter for cutting a coiled band includes a main body, and a cutting base installed on the main body, having a rectangular frame and a cutting groove formed in the long bottom side of the frame. Respectively fixed at one side and two ends of the cutting base is a sliding plate that has a sliding rail pivotally connected with two ends of a pressing rod respectively, so as to let the front end of the coiled band pass under the pressing rod to run out of the frame while having the pressing rod lifted up. Then, the pressing rod is released to press on the coiled band so as to let a knife unit pivotally connected with the main body flatly and securely cut the coiled band. The cutter is convenient and safe to use, with a cut band being flat and straight.