An object of the present invention is to provide an ultrasonic bonding tool capable of bonding a lead wire, without any trouble, even to a surface of a thin-film base having a plate thickness of 2 mm or less such as a glass substrate. In the present invention, a surface portion of a chip portion (1c) of an ultrasonic bonding tool (1) used in an ultrasonic bonding apparatus has a plurality of planar portions (10) formed so as to be separated from one another, and a plurality of concavities (11) formed between the plurality of planar portions. Each of the plurality of planar portions (10) has a flatness of 2 μm or less.