The semiconductor device uses an insulating resin that contains at least a resin anti-repellent for adjusting wettability of the insulating resin. The insulating resin is applied on a circuit board, and a semiconductor element is placed thereon and pressed against it. The applied pressure pushes out a portion of the insulating resin under the semiconductor element. This portion of the insulating resin combines with a portion of the insulating resin around the semiconductor element to form a resin fillet on the side surfaces of the semiconductor element.