A semiconductor element cooling apparatus includes: a first member whose first surface on which a semiconductor element is mounted, and whose second surface has fins that define coolant flow paths, and that extend in a first direction, and that stand from the second surface to a predetermined height, and that are spaced from each other by predetermined intervals; and a second member that defines the coolant flow paths that extend in the first direction. The fins have grooves which extend in a second direction that intersects the first direction, and which have a depth that extends from the distal end side of the fins toward the second surface. The depth of the grooves is smaller than the height of the fins. A protrusion-forming member is disposed in the grooves, and extends across adjacent fins, and forms protrusions in the coolant flow paths defined by the adjacent fins.