A capacitor arrangement structure includes a casing, a housing, and a heat sink. The casing accommodates a capacitor. The casing includes a casing bottom. The housing includes a bottom wall. The housing has a height from the bottom wall which includes an inner surface and an outer surface opposite to the inner surface in a height direction. The casing is mounted on the inner surface so that the casing bottom opposes a mounting surface in the inner surface. The heat sink includes a heat sink top. The heat sink is provided on the outer surface of the bottom wall not to overlap the casing viewed along the height direction. The heat sink top opposes the outer surface. A distance between the casing bottom and the mounting surface in the height direction is smaller than a distance between the heat sink top and the mounting surface in the height direction.