A packaging method includes ultrasonically bonding a semiconductor device and a substrate together via bumps that include gold as a main component thereof. A contact surface of a primary bump on a surface of an aluminum pad on one side of the substrate contacts and is ultrasonically bonded to a distal end surface of each opposed secondary bump on one side of the semiconductor device. An area of the contact surface is larger than that of the opposed distal end surface. By this method, damage to the substrate from the ultrasonic can be reduced without using a reinforcing layer.