PURPOSE: To control the rotation from the start to steady-state in a considerably stable manner by detecting a servo sector in accordance with a second counting value when the rotation reaches a predetermined rotating number, and controlling the rotating number corresponding to the detecting cycle.

CONSTITUTION: A servo sector is detected in accordance with a first counting value until a magnetic recording medium reaches a predetermined rotating number. When the rotating number becomes a predetermined number, a servo sector is detected by a second counting value. The rotating number is controlled corresponding to the detecting cycle. In other words, it is detected whether or not a spindle motor 10 is in the stationary rotating state. In the case of 'YES', the rotation of the spindle motor 10 is decelerated from the maximum rotating state nearly to the steady-state rotating state. A load data Dr for turning the spindle motor in the steady-state rotating state is set in a byte counter 7. Then, a current output at the interruption time is set to be enabled. Therefore, a current instruction value resulting from the interruption process becomes effective, thus controlling the rotation at the stationary rotating time. In this manner, the rotation can be controlled considerably stably from the start to the steady-state.