PURPOSE: To apparently perform an erasure-write procedure in an actual time without erasing existing information more than needed and preserving record effectively, by holding erasure until a prescribed quantity of information to be recorded is detected, and starting the erasure when holding is canceled.

CONSTITUTION: A data 309 transferred from the outside is stored is a buffer 303 in a sequence of an address number via a control part 301. Meanwhile, the information from the control part 301 is sent to a processor 307 via a register 302. Also, the storage address of the information outputted from the buffer is sent to the processor 307 by a control part 305 via a register 306. When the access of an optical head 204 to a recording start position is recognized by the information from a control part 201, the processor 307 calculates an information quantity accumulated in the buffer 303 and compares it with a set value. The erasure is held until the information quantity arrives at the set value, and when it arrives at the set value, the erasure is started.