There is provided a technology capable of suppressing the damage applied to a pad. When the divergence angle of an inner chamfer part is smaller than 90 degrees, the ultrasonic conversion load in a direction perpendicular to the surface of the pad is very small in magnitude. In other words, the ultrasonic conversion load in a direction perpendicular to the surface of the pad is sufficiently smaller in magnitude than the ultrasonic conversion load in a direction in parallel with the surface of the pad. Consequently, when the divergence angle of the inner chamfer part is smaller than 90 degrees, the ultrasonic conversion load in a direction perpendicular to the surface of the pad can be sufficiently reduced in magnitude, which can prevent pad peeling.