A fan holder (10) of the present invention includes a rectangular base (11). The base includes a first surface (12) and a second surface (13) opposite to the first surface and has an opening (14) defined in a center thereof. Two clamping arms (16) extend perpendicularly from opposite side edges of the first surface of the base, the arms having hooks (17) formed inwardly at ends thereof for sandwiching the fan (20) therebetween. Two clamping tabs (18) extend perpendicularly from opposite side edges of the second surface of the base in directions away from the clamping arms. Each clamping tab has a hook (19) formed outwardly at an end thereof. The fan holder is firmly secured to the heat sink (30), with the clamping tabs supported on two protrusions (35) formed at two fins (34) of the heat sink and the hooks of the tabs engaged with the heat sink.