Provided are: a reticular resin molding that is capable of controlling, by applying electrostatic charge to, air introduced into a heat exchanger and improving heat-exchange efficiency in said heat exchanger; and a method for operating an air-conditioner. This reticular resin molding has a plate-like shape, is made of a thermoplastic resin, has multiple vent holes penetrating in the thickness direction thereof, and enables improvement of heat-exchange efficiency of a heat exchanger by introducing electrostatically charged and controlled air into the heat exchanger through the vent holes. The resin molding is composed of a thermoplastic resin of polyethylene or polypropylene that has dissolved therein unbaked powder of a montmorillonite-based clay mineral. Meanwhile, the air-conditioner operating method according to the present invention involves disposing said reticular resin molding within the airflow path to a heat exchanger, and introducing air, having passed through the vent holes, into the heat exchanger.