PURPOSE: To stably and properly record in a long time by fetching a target value, etc., at the time of performing so as to become a fixed asymmetry to a test write area and a data write area as an initial value and a present value, and deciding the present value of the target value from them.

CONSTITUTION: When data is written in a DRAW type optical disk 5 by a control means 2, first of all, in the test write area 5a, the target values LP1, a pit level P1 and a land level L1, and read output level R1 at the time of performing so as to become the fixed asymmetry are stored as the initial values LPi, Pi, Li, Ri. Then, when the data is written in the data write area 5b, the present target value LP1, the pit level P1 and the land level L1, and the read output level R1 are fetched as the present values LPn, Pn, Ln, Rn. Then, this device is controlled so that the present value LPN of the target value is decided newly based on these initial values and present values.