A cutting insert (1) includes at least one cutting edge (8) formed on an intersecting ridge line portion between a rake surface (6) and a flank (7), and at least one ridge (12). The cutting edge includes a cutting edge portion (9) extending along a corner portion (5) and a straight-line shaped cutting edge portion (10) connecting to the cutting edge portion (9). The ridge (12) is formed to rise on the rake surface (6). The ridge (12) extends from a portion of a rake surface inside the cutting edge portion of the corner portion toward a rake surface inside the straight-line shaped cutting edge portion.