A cutting insert , comprising: an insert body in a prism shape; a rake face on an upper surface at an end portion of the insert body in a longitudinal direction; a front cutting edge on a ridge line between the rake face and an end surface of the insert body ; side cutting edges on ridge lines between the rake face and side surfaces of the insert body , being respectively connected to the front cutting edge ; and a breaker convex portion on the rake face , wherein the breaker convex portion includes two breaker island portions which extend such that when the two breaker island portions are considered in a direction moving towards the end surface, the two breaker island portions each get closer to the nearest side surface of the side surfaces, wherein each of the breaker island portions includes a first raised portion , a descending portion which gradually becomes lower from a top portion of the first raised portion , and a second raised portion which gradually becomes higher, from the descending portion , than the top portion of the first raised portion , wherein the first raised portion , the descending portion and the second raised portion are provided in this order in a direction from the end surface toward a center portion of the insert body , and wherein, between the two breaker island portions , a breaker groove and a center raised portion are provided such that the breaker groove is located between the center raised portion and the front cutting edge , and both side ends of the center raised portion are respectively coupled to the two breaker island portions , characterized in that a top portion of the second raised portion of the two breaker island portions is higher than a top portion of the center raised portion . an insert body in a prism shape; a rake face on an upper surface at an end portion of the insert body in a longitudinal direction; a front cutting edge on a ridge line between the rake face and an end surface of the insert body ; side cutting edges on ridge lines between the rake face and side surfaces of the insert body , being respectively connected to the front cutting edge ; and a breaker convex portion on the rake face , wherein the breaker convex portion includes two breaker island portions which extend such that when the two breaker island portions are considered in a direction moving towards the end surface, the two breaker island portions each get closer to the nearest side surface of the side surfaces, wherein each of the breaker island portions includes a first raised portion , a descending portion which gradually becomes lower from a top portion of the first raised portion , and a second raised portion which gradually becomes higher, from the descending portion , than the top portion of the first raised portion , wherein the first raised portion , the descending portion and the second raised portion are provided in this order in a direction from the end surface toward a center portion of the insert body , and wherein, between the two breaker island portions , a breaker groove and a center raised portion are provided such that the breaker groove is located between the center raised portion and the front cutting edge , and both side ends of the center raised portion are respectively coupled to the two breaker island portions , characterized in that a top portion of the second raised portion of the two breaker island portions is higher than a top portion of the center raised portion . <EOS>