A gear cutting insert comprising a first end surface and a second end surface which are located opposite each other and a peripheral side surface extending between the first end surface and the second end surface and comprising two side surface portions (20, 24), the cutting insert comprising an axis defined therein which extends so as to penetrate the first end surface and the second end surface, the cutting insert comprising: two first cutting edges (30, 32) with a curve shape, one first cutting edge being formed so as to extend along an intersecting ridge portion between the first end surface and one side surface portion of the two side surface portions and in such a manner that the one side surface portion functions as a rake face, the other first cutting edge being formed so as to extend along an intersecting ridge portion between the first end surface and the other side surface portion of the two side surface portions and in such a manner that the other side surface portion functions as a rake face, each of the first cutting edges being formed on the intersecting ridge portion between the first end surface and the related side surface portion so as to curve in a direction orthogonal to the axis; and two second cutting edges (34, 36) with a curve shape, one second cutting edge being formed so as to extend along an intersecting ridge portion between the second end surface and one side surface portion of the two side surface portions and in such a manner that the one side surface portion functions as a rake face, the other second cutting edge being formed so as to extend along an intersecting ridge portion between the second end surface and the other side surface portion of the two side surface portions and in such a manner that the other side surface portion functions as a rake face, each of the second cutting edges being formed on the intersecting ridge portion between the second end surface and the related side surface portion so as to curve in the direction orthogonal to the axis; characterized in that each of the first cutting edges (30, 32) and the second cutting edges (34, 36) is formed so as to have an involute curve shape for forming a tooth of an involute gear by transferring said involute curve shape to a workpiece. two first cutting edges (30, 32) with a curve shape, one first cutting edge being formed so as to extend along an intersecting ridge portion between the first end surface and one side surface portion of the two side surface portions and in such a manner that the one side surface portion functions as a rake face, the other first cutting edge being formed so as to extend along an intersecting ridge portion between the first end surface and the other side surface portion of the two side surface portions and in such a manner that the other side surface portion functions as a rake face, each of the first cutting edges being formed on the intersecting ridge portion between the first end surface and the related side surface portion so as to curve in a direction orthogonal to the axis; and two second cutting edges (34, 36) with a curve shape, one second cutting edge being formed so as to extend along an intersecting ridge portion between the second end surface and one side surface portion of the two side surface portions and in such a manner that the one side surface portion functions as a rake face, the other second cutting edge being formed so as to extend along an intersecting ridge portion between the second end surface and the other side surface portion of the two side surface portions and in such a manner that the other side surface portion functions as a rake face, each of the second cutting edges being formed on the intersecting ridge portion between the second end surface and the related side surface portion so as to curve in the direction orthogonal to the axis; characterized in that each of the first cutting edges (30, 32) and the second cutting edges (34, 36) is formed so as to have an involute curve shape for forming a tooth of an involute gear by transferring said involute curve shape to a workpiece.