A heat dissipation device includes a heat sink forming an engaging portion along an outer periphery thereof, a fan holder attached to the heat sink and a fan secured to the heat sink via the fan holder. The fan holder includes an elastic main body, a first clip pivotally connected to a free end of the elastic main body and a second clip connected with the first clip and engaging with an opposite free end of the elastic main body. The elastic main body includes a pair of fixing portions formed at upper and lower sides thereof. The lower fixing portion of the fan holder is tightly engaged with the engaging portion of the heat sink and the upper fixing portion presses the fan towards the heat sink when the second clip is tightly locked to the opposite free end of the elastic main body.