An ultrasonic-welding apparatus including: a cradle, onto which two work pieces
are mounted, and which can rotate around an axis vertical to the welding surface
of the work pieces; a welding horn, which carries out welding using ultrasonic
energy while sandwiching the two work pieces between it and the cradle; a transmission-type
laser sensor which measures the fixed part of the work pieces after welding, rotating
on the cradle, in the condition that the welding horn is apart from the work pieces
after welding; and an optical sensor including a light-emitting part, a light-receiving
part, a connecting part on which the light-emitting and light-receiving parts are
mounted, and an adjusting part that rotates the connecting part around two axes.
