A cutting insert may include a first surface, a second surface, a first lateral surface, a second lateral surface, a first cutting edge and a second cutting edge. The first lateral surface may include a first inclined surface located along the first cutting edge, a second inclined surface located along the first inclined surface, a third inclined surface located along the second cutting edge, a fourth inclined surface located along the third inclined surface, and a flat surface located along the second inclined surface and the fourth inclined surface. A second inclination angle of the second inclined surface may be smaller than a first inclination angle of the first inclined surface. A fourth inclination angle of the fourth inclined surface may be larger than a third inclination angle of the third inclined surface.