Patent ID: 8495668

Claim:
A disc drive apparatus, comprising: a spindle motor, which is configured to hold and rotate a disc; an optical head, which is configured to conduct either one of recording or reproducing of information onto/from the disc; a driver unit, which is configured to move the optical head in a radial direction of the disc; and a unit mechanism chassis, which is configured to support the spindle motor, the optical head and the driver unit thereon, fixedly, wherein the spindle motor is constructed with a rotational drive means made of a magnetic circuit, a rotor portion and a rotation shaft, which define a rotation body, and a spindle motor attachment plate to hold the rotational drive means, the rotor portion and the rotation shaft thereon, the spindle motor attachment plate has a semi-circular shaped plate portion in a part thereof, nearly fitting to an outer diameter the rotor portion, in a direction where the optical head is provided, and has a step-like structure in thickness direction of the plate thereof, and the step-like structure is provided on the spindle motor attachment plate, and extends from the semi-circular shaped plate portion to a region which is an opposed portion to the semi-circular shaped plate portion in the spindle motor attachment plate so as to bridge over a line connecting between corner portions on both ends of the semi-circular shape plate portion.