A motor comprising: an iron core; and an insulator disposed on an axial end surface of the iron core, wherein the iron core includes at least one groove (22, 23) on an outer circumferential portion, wherein the groove (22, 23) is arranged in an axial direction of the iron core on the outer circumferential portion from the end surface of the iron core, wherein the iron core includes a core back portion extending in a circumferential direction, a tooth portion protruding in a central direction from a middle portion of the core back portion, and a tooth end portion located at an end of the tooth portion, wherein the insulator includes at least one first protrusion (16, 17) protruding in the axial direction from a surface in contact with the iron core, wherein the first protrusion (16, 17) is contained within the groove (22, 23), wherein the insulator includes at least one second protrusion (18, 19) protruding in the axial direction from the surface in contact with the iron core, and wherein the second protrusion (18, 19) is in contact with an inner circumferential surface of the tooth end portion, and the insulator holds the iron core, characterized in that the groove (22, 23) is arranged at a part of an outer circumferential portion of the core back portion that does not overlap a projection of the tooth portion onto a plane of the core back portion, wherein the second protrusion (18, 19) is in contact with the inner circumferential surface of the tooth end portion at a part of the tooth end portion that does not overlap a projection of the tooth portion onto a plane of the tooth end portion. an iron core; and an insulator disposed on an axial end surface of the iron core, wherein the iron core includes at least one groove (22, 23) on an outer circumferential portion, wherein the groove (22, 23) is arranged in an axial direction of the iron core on the outer circumferential portion from the end surface of the iron core, wherein the iron core includes a core back portion extending in a circumferential direction, a tooth portion protruding in a central direction from a middle portion of the core back portion, and a tooth end portion located at an end of the tooth portion, wherein the insulator includes at least one first protrusion (16, 17) protruding in the axial direction from a surface in contact with the iron core, wherein the first protrusion (16, 17) is contained within the groove (22, 23), wherein the insulator includes at least one second protrusion (18, 19) protruding in the axial direction from the surface in contact with the iron core, and wherein the second protrusion (18, 19) is in contact with an inner circumferential surface of the tooth end portion, and the insulator holds the iron core, characterized in that the groove (22, 23) is arranged at a part of an outer circumferential portion of the core back portion that does not overlap a projection of the tooth portion onto a plane of the core back portion, wherein the second protrusion (18, 19) is in contact with the inner circumferential surface of the tooth end portion at a part of the tooth end portion that does not overlap a projection of the tooth portion onto a plane of the tooth end portion.