Cutting insert and cutting tool on which same is mounted

A cutting insert comprising an upper surface, a lower surface, a lateral surface, a cutting edge, and a fastening hole, wherein

• the cutting edge includes a main cutting edge, a nose R part connected to the main cutting edge, and a sub-cutting edge connected to the nose R part,
• the upper surface includes a land part adjacent to the cutting edge, an inclined surface downwardly inclined from the land part, and an upper surface bottom part extending from the inclined surface,
• the land part includes a main cutting edge land part adjacent to the main cutting edge, a nose R part land part connected to the main cutting edge land part and adjacent to the nose R part, and a sub-cutting edge land part connected to the nose R part land part and adjacent to the sub-cutting edge,
• the inclined surface includes a main cutting edge inclined surface downwardly inclined from the main cutting edge land part, a nose R part inclined surface connected to the main cutting edge inclined surface and downwardly inclined from the nose R part land part, and a sub-cutting edge inclined surface connected to the nose R part inclined surface and downwardly inclined from the sub-cutting edge land part, and
• first and second protrusion parts are formed respectively, wherein the first protrusion part is connected to the main cutting edge land part and formed on the main cutting edge inclined surface at a portion at which the nose R part inclined surface ends, and the second protrusion part is connected to the sub-cutting edge land part and formed on the sub-cutting edge inclined surface at a portion at which the nose R part inclined surface ends, and no protrusion is present on the nose R part inclined surface.