Abstract: An information correcting method includes: detecting a first pattern in a radial direction and a second pattern formed obliquely to the radial direction on a track traversing the first and second patterns; counting number of the first pattern until the count value reaches number of the first pattern in one round of the track; generating a value incremented up number of the second pattern in the one round every time an interrupt associated with detection of the second pattern is generated as number of the second pattern; calculating an ideal number from a value obtained by multiplying the number of the second pattern until the number is counted by the counted number of the detected first pattern and a number set to the second pattern with reference to the second pattern formed at a present initial position; and correcting the generated number with the ideal number.