A masking apparatus includes a mask base body and a mask plate. The mask base body includes at least one spacer plate, and a cavity in which an electronic component can be housed. The mask plate is disposed on an upper surface and/or a lower surface of the mask base body. The mask plate includes a film-forming opening with a shape corresponding to the shape of an external structural body to be formed on an outer surface of the component. The mask plate thus allows a film-forming operation to be selectively performed on the outer surface of the component through the film-forming opening. The cavity includes, in an inner surface thereof, a film-forming groove communicating with the film-forming opening so that the external structural body can be formed at once on an upper surface and/or a lower surface of, and also on a peripheral surface of the component.