Abstract: An evaporator of a capillary pumped loop (CPL) cooling apparatus having a fine wick structure is provided. The evaporator having a flat board shape, of a capillary pumped loop (CPL) cooling apparatus includes a coolant storing part for storing in-flowing coolant from the condenser and collecting a uncondensed gas contained in the in-flowing coolant in an upper space, a cooling part for cooling the heating body through vaporization of the coolant, and superstructure and substructure combined with each other, for defining a channel region in which the coolant flows from the coolant storing part to the cooling part by a capillary action. In this case, the substructure includes a first substructure used as a substrate and a second substructure formed along a border of the substrate, or includes first through third segments equal to the first and second substructures.