An axial-gap type motor comprising a stator statically held by a housing, and a rotor supported so as to be rotatable relative to the stator, either one of the stator and the rotor including: a yoke-provided core including a back yoke of an annular shape concentric with a rotational shaft of the rotor, and a plurality of magnetic pole cores projecting in a direction of the rotational shaft of the rotor from a side surface of the back yoke so as to form magnetic poles which are parallel to the rotational shaft of the rotor; and coils wound around the respective magnetic pole cores, wherein the yoke-provided core is a core-pieces-arrayed body consisting of core pieces arrayed in a circumferential direction of said yoke and separated from each other along a division line corresponding to the respective magnetic pole cores, each core piece including a magnetic pole core portion which is a part of the corresponding magnetic pole core, and a back yoke portion which is a part of the back yoke, and each core piece being a steel plate laminate consisting of a plurality of steel plates stacked in a radial direction of the rotational shaft, wherein the division line is made at an intermediate location in width, in a rotor circumferential direction, of each magnetic pole core, and, in each core piece, the magnetic pole core portion includes two magnetic pole core half portions which are respective parts of adjacent two of the magnetic pole cores, and the back yoke portion extends between the two magnetic pole core half portions, characterized in that each core piece is composed of a plurality of core piece bodies (7AI, 7A0) arrayed in a rotor radial direction, the plurality of core piece bodies (7AI, 7A0) being different from one another in width in the rotor circumferential direction, wherein, among the core piece bodies (7AI, 7A0), a core piece body having a larger width (7A0) is located on an outer side in the rotor radial direction and a core piece body (7AI, 7A0) having a smaller width is located on an inner side in the rotor radial direction, and portions, of each core piece body (7AI, 7A0), which serve as the magnetic pole core half portions each have an even width in the rotor circumferential direction. a stator statically held by a housing, and a rotor supported so as to be rotatable relative to the stator, either one of the stator and the rotor including: a yoke-provided core including a back yoke of an annular shape concentric with a rotational shaft of the rotor, and a plurality of magnetic pole cores projecting in a direction of the rotational shaft of the rotor from a side surface of the back yoke so as to form magnetic poles which are parallel to the rotational shaft of the rotor; and coils wound around the respective magnetic pole cores, wherein the yoke-provided core is a core-pieces-arrayed body consisting of core pieces arrayed in a circumferential direction of said yoke and separated from each other along a division line corresponding to the respective magnetic pole cores, a yoke-provided core including a back yoke of an annular shape concentric with a rotational shaft of the rotor, and a plurality of magnetic pole cores projecting in a direction of the rotational shaft of the rotor from a side surface of the back yoke so as to form magnetic poles which are parallel to the rotational shaft of the rotor; and coils wound around the respective magnetic pole cores, wherein the yoke-provided core is a core-pieces-arrayed body consisting of core pieces arrayed in a circumferential direction of said yoke and separated from each other along a division line corresponding to the respective magnetic pole cores, each core piece including a magnetic pole core portion which is a part of the corresponding magnetic pole core, and a back yoke portion which is a part of the back yoke, and each core piece being a steel plate laminate consisting of a plurality of steel plates stacked in a radial direction of the rotational shaft, wherein the division line is made at an intermediate location in width, in a rotor circumferential direction, of each magnetic pole core, and, in each core piece, the magnetic pole core portion includes two magnetic pole core half portions which are respective parts of adjacent two of the magnetic pole cores, and the back yoke portion extends between the two magnetic pole core half portions, characterized in that each core piece is composed of a plurality of core piece bodies (7AI, 7A0) arrayed in a rotor radial direction, the plurality of core piece bodies (7AI, 7A0) being different from one another in width in the rotor circumferential direction, wherein, among the core piece bodies (7AI, 7A0), a core piece body having a larger width (7A0) is located on an outer side in the rotor radial direction and a core piece body (7AI, 7A0) having a smaller width is located on an inner side in the rotor radial direction, and portions, of each core piece body (7AI, 7A0), which serve as the magnetic pole core half portions each have an even width in the rotor circumferential direction.