NOVELTY - The apparatus has an adsorption unit which adsorbs gas by irradiating electromagnetic waves to the adsorbent which adsorbs/desorbs gas from the adsorbent (1), and expands the volume of the gas. A changing unit changes the volume of the taking out gas by repeatedly adsorbing the gas using adsorbent. A shrinkage unit shrinks the volume of the gas as the motive power source by interrupting the electromagnetic wave. An electromagnetic wave shielding board (6) switches the interruption of the adsorbent holding unit (2).    USE - Power generation apparatus of electric power generation system used in air conditioning system (all claimed).    ADVANTAGE - The power generation apparatus can effectively transform the electromagnetic wave into the kinetic energy efficiently with simple structure. The energy consumption of the air conditioning system is reduced, so that pollution to the environment can be prevented effectively. The adsorption efficiency of the power generation apparatus can be improved effectively.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) electric power generation system generates electric power under the motive power generated with the power generation apparatus has adsorbent holding unit that is provided with an electromagnetic wave transmission window (8) for transmitting electromagnetic waves. The piston (4) is fitted in the cylinder. The electromagnetic waves are selected from the UV-ray, a visible ray, infrared ray, sunlight, heat ray and radiant heat. The adsorbent is provided with the cross-linking polyacrylate type polymer compound and photo-thermal conversion material. A cooling unit cools the adsorbent. ; and    (2) air conditioning system air-conditions under the motive power generated with the power generation apparatus.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the power generation apparatus.    Adsorbent (1)    Adsorbent holding unit (2)    Piston (4)    Electromagnetic wave shielding board (6)    Electromagnetic wave transmission window (8)