An attaching device is provided for mounting and fixing a semiconductor device
and a heat sink provided on the semiconductor device on a board. The attaching
device includes a base part fixed to the board, a rotation member provided to the
base part rotatably, the rotation member rotated and received at the base part
so that the semiconductor device is fixed to the board, and a press mechanism that
presses the heat sink to the semiconductor device when the rotation member is rotated.