To obtain a method of ultrasonic bonding with high bonding strength by fully applying a bump with an ultrasonic wave by controlling a speed at which the bump is collapsed immediately after the ultrasonic wave is applied.

The method of ultrasonic bonding for bringing a bonding tool into contact with the other main surface of a component 4 in which the bump is formed on one main surface, applying a pressing force and an ultrasonic vibration to the component 4 and bonding the bump to a surface 2 to be connected includes a first step of lowering the bonding tool at a substantially constant speed while applying the ultrasonic wave at the initial stage of bonding the bump to the surface to be bonded and controlling the collapsing speed of the bump, and a second step of applying the substantially constant pressing load to the bonding tool while applying the ultrasonic wave after the first step and bonding the bump to the surface to be bonded. The bump is gradually collapsed by controlling the bump collapsing speed at the bonding initial stage, and the ultrasonic vibration can be sufficiently operated at a bonding part.