Information recording and reproducing apparatus and an information recording and reproducing method

Recording condition adjusting device of the present invention is used for the adjustment of recording conditions of the first recording pattern and, one recording length unit short marks and spaces than the predetermined recording length used for adjusting recording conditions of a predetermined record length or more marks and spaces the by using a second recording pattern, to adjust the recording condition. 1 If the re-adjustment is deemed necessary for the recording length unit shorter mark recording adjusted at the determined recording condition, and sets the signal index value determined based on the first recording pattern to the target value. As the signal index value corresponding to one recording length unit shorter mark approaches the target value, to readjust the one recording length unit shorter mark recording conditions.