In the present invention, there is disclosed an electrical induction apparatus having a magnetic core unit being comprised of a toroidal magnetic core and at least one winding wound around the core and a casing for housing the magnetic core unit therein, comprising a support plate for supporting the bottom of the magnetic core unit having at least one opening, means for positioning the unit at a predetermined position in the casing being engageable to the opening of the support plate, a cylindrical member made of an insulating material which is so formed as to fit into the central hole of the unit, a mounting plate for fixing the unit being disposed on the top of the unit, an axial member passing through the central hole of the cylindrical member, one end of which is connected to the supporting plate and the other end of which is projected outwardly in the axial direction thereof, a nut means for fastening the mounting plate to hold the unit between the mounting plate and the support plate which is engageable to a threaded portion provided on the other end of the axial member, wherein the mounting plate is fixed to the casing so as to hang the unit in the casing.