PURPOSE: To drive a disk with less torque and good balance and to improve the life of a slider by eliminating the need for specific positioning and decreasing the burden of a motor.

CONSTITUTION: Ring electrodes 22 connected to a RAM 18 arranged in the unrecording region 14 of an information recording disk 10 are formed to a concentrical circle with the center of the disk and come into contact with spring electrodes 34 on a driving device side in a symmetrical position. These spring electrodes 34 are connected to sliding electrodes 38 formed along a revolving shaft 36. The slider at the front end of an arm part 44 comes into contact with these sliding electrodes 38 only when the RAM 18 is accessed by a plunger mechanism. The torque load of a spindle motor is thereby decreased and the consumption of the slider is reduced as well.