A mounting apparatus for mounting a heat sink on a board, includes a first locking hole defined in the heat sink, a second locking hole defined in the board, and a locking member. The locking member includes a base and a rod. The base defines a hole. A bottom of the base forms a pair of separated elastic claws around the hole. The elastic claws are inserted through the first and second locking holes. The rod includes an expanded portion. The rod slides in the hole of the base with the expanded portion located inbetween the claws to expand the claws outwards to be larger than the second locking hole to lock the locking member on the board and to mount the heat sink on the board.