Abstract: A gas dehumidifying apparatus including a dehumidifier rotor wherein the rotor is of a composite construction which is compatible with both high humidity and low humidity conditions and in which proper temperature conditions can be obtained in connection with the regeneration of the adsorbent to thereby improve the adsorption performance of the rotor. The apparatus exhibits improved dehumidification efficiency and thus can provide treated gas with a dryness level higher than conventionally attainable.