Disclosed is a cutting tool for milling works which employs a cutting insert. The cutting tool for milling works employs a cutting insert. By forming a concave nick cutting edge on the lateral surface of the cutting insert, it may cut a chip in a short form in case of high depth of cutting to shorten the effective cutting edge, so as to reduce a friction and a cutting resistance, thereby increasing the life span of the cutting tool as well as to facilitate a chip disposal and reduce the cutting resistance, so as to increase a feed rate at a high depth of cutting, thereby enhancing the productivity of the cutting works. By forming concave recesses on the upper and lower surfaces of the cutting insert it may reduce the cutting resistance between the chip being short cut by the concave nick cutting edge and the upper and lower surfaces. By forming a concave nick cutting edge at a major cutting edge of the cutting insert it is possible to perform a nick cutting edge function without deforming the seat lateral surface of a seat portion to couple the cutting insert with a cutter body.