Disclosed herein is a magnetic disk apparatus such as a hard disk apparatus or a removable hard disk apparatus which allows switching of the speed of rotation of a magnetic disk while assuring a sufficient tracking control characteristic and a sufficient capacity. More concretely, a magnetic disk apparatus of the present invention, in which tracking of a magnetic head is controlled with reference to a plurality of servo areas formed at predetermined angular distances on a magnetic disk to access the magnetic disk, includes; the servo areas being formed in synchronism with a fixed clock signal such that reference patterns for tracking control are formed therein, a clock generation means for generating a clock signal common to the plurality of servo areas with reference to reproduction signals obtained from the servo areas, a tracking control signal generation means for generating a control signal for tracking control from the reference patterns with reference to the clock signal, a tracking control means for controlling tracking of said magnetic head with reference to the control signal, and a speed switching means for switching the speed of rotation of the magnetic disk.