motor or optical disk here the reference radial position mentioned above is set to an appropriate value in advance based on the conditions of the servo system such as torque characteristics of the disk motor 300 the inertia of the body of rotation and the like hereinafter the elements of fig1 used in the description of fig2 and 3 are denoted by the same reference numerals as those in fig1 fig2 a to 2 c are diagrams for describing disk rotation control when the disk is accessed in the optical disk apparatus of fig1 fig2 a to 2 c illustrate the case when the write operation is performed through the accessing operation fig2 a is a radial cross sectional view of the optical disk 100 fig2 b is a diagram showing a relationship between the disk radial position where the data is written and the rotation speed of the optical disk 100 disk rotation speed and fig2 c is a diagram showing a relationship between the disk radial position where the data is written and the recording velocity in fig2 a to 2 c r i designates the innermost disk radial position of a user data recording area of the optical disk 100 r o designates the outermost disk radial position of the user data recording area p designates the reference radial position a 1 shows characteristics of the disk rotation speed in the case of 5 u00d7 speed recording using the constant linear velocity method clv recording b 1 shows characteristics of the disk rotation speed in the case of recording with the 3 u00d7 speed rotation using the constant angular velocity method cav recording a 2 shows characteristics of the recording velocity in the case of the 5 u00d7 speed recording using the constant linear velocity.