To provide a heatsink having heat radiation performance satisfactory regardless of the direction of a wind.

Two or more fins 31 to 39 are erected side by side so that the faces of fins adjacent to each other may face each other, and the heights of the respective fins are increased in order of getting nearer to inner side of an arranging direction. The fins are provided with one or more notches along the height direction, the fins are provided with one or more through holes in the thickness direction of the fins, or the fins are wave-formed. As a solving means concerning a base station apparatus, the heatsink 2 composed of two or more fins, a ventilation sheet metal which can be fitted to the rim of the casing 1 of the base station apparatus and a fan fitted to one or more faces of the ventilation sheet metal are provided integrally with the casing.