Information recording/reproducing apparatus and information recording method

An information recording method using a read modify write operation includes determining whether a write command is inconsistent or not, on the basis of a unit of a cluster. When the write command onto the rewritable type optical disk needs verification and the read modify write operation is executed, then a verify process is conducted only upon a part of the information, which is written through the read modify write operation. The method achieves an increase in recording speed and an improvement on reliability of recorded information through the read modify write, even when the verify process is unnecessary.