Patent ID: 7894158

Claim:
A magnetic disk apparatus, comprising: a magnetic recording medium; a magnetic head assembly having a magnetic head which records information in a target track as an access target, or reads out information from the target track in tracks formed on the magnetic recording medium, which moves on a prescribed moving locus to transport the magnetic head to the target track; a spindle motor rotation body fixed to the magnetic recording medium; a motor coil assembly rotationally driving the spindle motor rotation body, in which plural motor coils are arranged on a circumference around the rotation center of the spindle motor rotation body so that all intervals in the circumferential direction are substantially equal; and a stator base surrounding a periphery of the spindle motor rotation body, wherein a shape of the stator base comprises a cut out portion, wherein the cut out portion enables a prescribed moving locus portion of the magnetic head assembly to move to an inner circumference side of the magnetic recording medium, wherein an arrangement internal for the plural motor coils is equal to or greater than a sum of (a) a central angle of the cut out portion and (b) a central angle corresponding to a width of each motor coil of the plural motor coils, and wherein the number of plural motor coils is a multiple of three.