An information recording and reproducing device diffracts by a diffracting means (14) to make laser light separated into a main beam and a sub-beam, irradiates evanescent light in relation to the main beam, by an evanescent light generating means (21), to a track where a recording pit provided on a recording surface of a recording medium is formed and also irradiates evanescent light in relation to the sub-beam to be separated to a track where no recording pit provided on the recording surface of the recording medium is formed. A moving means (210) moves the evanescent light generating means to a direction to change a gap with the recording surface. Further, a judging means (40) judges an uneven state of the recording pit formed on the recording medium, a signal generating means (3161) generates a gap error signal from a signal indicative of a return light amount in relation to the sub-beam or the main beam in accordance with the result, a control means (315) controls the moving means in accordance with a gap error signal so as to make the gap become a target value in response to the uneven state to be judged.