PURPOSE: To provide a rewritable card reader/writer device and a printing/ deleting method wherein the best printing can be obtained all the time by supplying optimal printing energy or erasing energy dependent on the number of rewrite times or reflection density.

CONSTITUTION: A device is equipped with a means for writing/reading the number of rewrite times in a rewrite card as a magnetic data, a means for storing printing energy or erasing energy dependent on the number of rewrite times, and a means for controlling printing energy to a thermal head 17 or erasing energy to a hot stamp 19. Dependent on the number of rewrite times, the printing energy to the thermal head 17 or the erasing energy to the hot stamp 19 is controlled.