A reactor according to an embodiment of the present disclosure includes a reactor main body including cores and coils wound on the cores; and a base having a polygonal shape extending outside the reactor main body, configured to support the reactor main body. In at least two sides that are not opposite each other, of a plurality of sides of the base, a plurality of notches are formed inwardly from each of the sides, so that axes of fasteners to temporarily secure the base to an installation target object pass through the notches.