Provided is an image erasing method including heating a thermoreversible recording medium with laser beams to erase an image which has been recorded on the thermoreversible recording medium, the thermoreversible recording medium reversibly changing between a colored state and a decolored state depending on a heating temperature and a cooling time; and measuring at least one of a surface temperature of the thermoreversible recording medium and an erasing environmental temperature before a beginning of erasing the image to obtain a measured temperature value and controlling a heating time with the laser beams to be emitted for erasing the image depending on the measured temperature value.