The improved upper magnetic plate for anchoring molds, is constituted by a body made of steel with high magnetic permeability in which recessed seats (3) are provided for accommodating coils (4) adapted to generate an attracting magnetic field, the improvement consisting in that the coils (4) are constituted by turns of wire (5) made of a material such as a fluorocarbon resin perfluor alkoxy (PFA) and wrapped by a peripheral containment lapping (7) made of an adhesive tape which has a vitreous base; the coils (4) are arranged in the corresponding recessed seats (3) and are locked therein by means of a thermosetting silicone containing filling material (8) which is initially inserted in the plastic and malleable state; the seats can be closed in an upward region with plates (9) made of diamagnetic material.