PURPOSE: To facilitate evaluation of the performance of a disc by a constitution where an optical member having an optical characteristic and other characteristics equal to those of an actual disc can be installed near the position of the disc.

CONSTITUTION: When a device 4 whose inside a test disc piece 40 is stuck to is attached to cap a case 31 where a focal lens or the like of a head is stored, the disc piece 40 is brought to a position where the original disc should be put. When an AF system is operated, the light spot in focused on a recording film of the disc piece 40. When a switch 54 is connected to a side 54-2, the signal of a TR system is cut off, and a driving coil 50 of a tracking actuator is driven through a buffer amplifier 53 and a driver 52 by the signal of an oscillator 56, and the light spot is shaked in the track direction with a certain amplitude. In this state, the performance of the disc is evaluated easily.