Abstract: A motor having improved mechanism is composed of a body of revolution having a mounting hole in the center of the body; a rotor hub having a boss section to be inserted into the mounting hole of the body of revolution and a flange section supporting the body of revolution; and an elastic plate installed coaxially to the rotor hub and pressing the body of revolution on the flange section of the rotor hub, wherein the elastic plate is provided with a plain section having a hole in the center and a plurality of arm sections extending radially from an outer circumference of the plain section, and wherein each of the arm sections is provided with a first slanting section that is inclined with respect to the plain section and a second slanting section having an angle of gradient different from that of the first slanting section, and further wherein the first slanting section contacts with an outer circumferential edge of the boss section that confronts with an inner wall surface of the mounting hole of the body of

Abstract: A spindle motor (100) is composed of a rotor section (R) having a chucking magnet (3) for sucking in a disc hub (11) made from a magnetic material, wherein the rotor section (R) is rotatably maintained with respect to a stator section (S). The chucking magnet (3) is further composed of a first magnet (3a) in almost an arc shape having a first width W1 in a radial direction and a second magnet (3b) in almost an arc shape having a second width W2 in a radial direction, wherein the first magnet (3a) is magnetized in a plurality of magnetic poles at a first angular interval P1 in a circumferential direction and the second magnet (3b) is magnetized in a plurality of magnetic poles at a second angular interval P2 in a circumferential direction, and wherein a relationship between each width and each angular interval satisfies an equation W1/W2=P1/P2.