A cutting insert, and more particularly, an improved double-sided cutting insert is provided, which provides improved machinability obtained due to increased rake angle, without compromising coupling state. The double-sided cutting insert includes a top surface, a bottom surface, a plurality of lateral relief surfaces connecting the top and bottom surfaces, and a cutting edge formed by the top and bottom surfaces and the plurality of lateral relief surfaces, in which one or more lateral relief surfaces of the plurality of lateral relief surfaces are formed into three stages in sequence which are a first positive surface, a negative surface and a second positive surface in a direction from the top surface to the bottom surface.