PURPOSE: To obtain an information recording device which can perform after recording without occurring imperfect erasing of data by providing a recording leading position calculating means and rewriting data based on position reference information.

CONSTITUTION: In an information recording device in which data is recorded by adding position reference information at the leading position of each recording unit in each recording region in which data of the prescribed quantity is made a recording unit, a recording start position detecting section 24 calculates a recording leading position of rewritten data based on a timing sync. signal and a discriminating signal obtained in a reproducing system. And it generates a recording start position pulse, and controls a multiplexer 7. Thus, by calculating the recording leading position of rewritten data based on the reference position information reproduced from the recording region and rewriting data, data recorded in a memory region adjacent of a region of discriminating information can be rewritten at high accuracy without occurring imperfect erasing.