A mounting device (10) for mounting a heat sink (20) to a printed circuit board (40) on which a heat generating electronic component (30) is disposed, includes a mounting frame (100), two clasping legs (104) and four resilient arms (105). The mounting frame includes two first mounting arms (101) and two second mounting arms (102) disposed above the first mounting arms. The first mounting arms abut on the circuit board. The clasping legs connect with the second mounting arms and are inserted through the printed circuit board to be attached to the printed circuit board. The resilient arms connect with the second mounting arms and exert a downward resilient force on the heat sink toward the heat generating electronic component.