Abstract: A writing condition adjusting apparatus according to the present invention adjusts a writing condition using first and second recording patterns. The first recording pattern is used to adjust a writing condition for recording marks and spaces, of which the lengths are equal to or longer than a predetermined recording length, while the second recording pattern is used to adjust a writing condition for recording marks and spaces, of which the lengths are shorter than the predetermined recording length by one recording unit length. If it has been decided that the writing condition that has once been determined by making the write adjustment on such marks that are shorter by one recording unit length needs to be adjusted again, a signal index value that has been defined based on the first recording pattern is set to be a target value.