PURPOSE: To prevent imperfect erasing at the time rewriting by a reflectivity difference between recording mark parts and parts exclusive thereof and to increase the number of reloadable times. CONSTITUTION: This optical recording medium is provided with a layer (reflectivity adjusting layer) 6 which is changed in optical constant by melting, etc., at the time of photoirradiation separately from a recording layer 8 by a phase transition, etc., and is so formed that the reflectivity of the part having the high reflectivity on recording tracks is =60% at the time of the irradiation with the weak light. The laser power of the optical disk device using such optical disk is set at the power higher than the power at which the optical constant of the reflectivity adjusting layer changes largely and at which the high melting component does not melt at the time of rewriting. The optical disk which has the high recording sensitivity, is readable out by a CD player, etc., and is reloadable by overwriting and the optical disk device using such disk are obtd. The overwriting characteristics are good and the number of rewriting times is large.