A semiconductor apparatus includes a housing in a shape of a panel, a cooling fan configured to exhaust from a top surface of the housing, and provided on the top surface, a partition plate configured to vertically partition a space below the cooling fan into a first space and a second space, and including opening portions through which a cooling airflow produced by the cooling fan passes from the first space to the second space, semiconductor units cooled by the cooling airflow, and vertically disposed in the first space, and a slit plate attached to at least one of the opening portions of the partition plate, and configured to limit an airflow speed of the cooling airflow.