A fan-shaped dissipating device, which is assembled on a chip of an erect PCB, has a conductive board, and a plurality of fins. The fins are respectively connected on an outside surface of the conductive board. Each of the fins has a top end and a bottom end. An interval between each two adjacent top ends of the fins is larger that between each two adjacent bottom ends of the fins. The fins are arranged in a radiating manner toward two sides from the bottom ends to the upper ends, therefore reducing the density of the accumulated air between the top ends of the fins because of rising hot air, and providing a better dissipating effect.