A pit edge interval correcting method in an optical recording/read-out apparatus wherein as data items to be used to correct pit edge intervals for cancellation of a thermal interference from a previously recorded pattern, there is formed a table representing relationships between kinds of record patterns and edge shift quantities of the patterns in a read-out signal. Edge shift quantities of particular patterns with respect to a unitary variation quantity of a recording medium surface temperature (an ambient temperature of an optical disk) and edge shift quantities of particular patterns with respect to a unitary variation quantity of laser power are beforehand acquired as correction control data. Before actual data are recorded, the particular patterns are again recorded on a medium and read out therefrom. If an edge shift occurs in a read-out signal, a variation quantity of the recording medium surface temperature and a variation quantity of the laser power are separately obtained based on a quantity of the edge shift occurring and the correction control data collected in advance. Using each variation quantity, the value set to the laser power is altered and/or the data in the table are updated to correct the actual data.