Provided is a heatsink comprising: a plurality of sheet-shaped heat-dissipating plates stacked on one another, each heat dissipating plate including a heat-absorbing region that has a lower end contacting a heat source to absorb heat from the heat source and a heat-dissipating region that extends from both sides of the heat-absorbing region to absorb heat from the heat-absorbing region and outwardly dissipate the heat, wherein the heat-absorbing regions are tightly joined to one another by applying an external pressure to form a central portion and the heat-dissipating regions are radially spread out about the central portion, wherein each of the heat-dissipating regions includes a long heat-dissipating region and a short heat-dissipating region, which are asymmetric with respect to the central portion. Accordingly, the heatsink can efficiently dissipate heat generated from the heat source mounted on an edge of a narrow circuit board by efficiently utilizing a space over the circuit board.