The present invention is installed between the filter of the suction grill and the blower fan so that fine particles or ultra-fine particles in the suction air are discharged to the room after the particles adhere to the particles through an electrostatic reaction, and thus the particles are re-suctioned. It relates to an ion cluster generating device of a fan coil unit that improves air purification performance because it is filtered by a filter and also removes harmful gases and odors through a photocatalytic action. To this end, the present invention includes a blower fan and a heat exchanger that are rotated by a motor inside the main body built in the ceiling, and an open bottom surface of the main body is provided with a cover having a central suction port and a discharge port in all directions, and a lower portion of the cover is provided. A plastering panel exposed to the room is provided. In the plastering panel, in the ion cluster generator of the fan coil unit equipped with a suction grill and a filter corresponding to the suction port, a cylindrical generator body placed at the center of the suction port is provided. , The lower end of the generator body is close to the filter, the upper end is close to the center of the blowing fan, and indoor air is guided to the blowing fan through a space between the inner periphery of the inlet and the outer periphery of the generator body； The generator body is divided into an ion chamber and a photocatalytic chamber through a partition wall； The ion chamber is provided with a high voltage generator that repeatedly generates negative charges and positive charges so that fine or ultra-fine dust in the indoor air sticks to each other through an ion cluster charged with negative or positive charges to increase the volume； In the photocatalyst room, an ultraviolet lamp is provided in the center of a cylindrical perforated network coated with a photocatalyst, so that indoor air is deodorized.본 발명은 흡입그릴의 필터와 송풍팬 사이에 설치되어
