Ultrasonic welding device and ultrasonic welding method

An ultrasonic welding device comprising:

• a support device configured so as to support a work piece along a predetermined conveyance surface,
• a welding machine including an oscillator for generating a high-frequency electric signal, a transducer for converting the high-frequency electric signal to a mechanical vibration, and a horn to which the mechanical vibration is transmitted, the horn being disposed so as to face a part to be welded of the work piece supported along the conveyance surface, and the mechanical vibration being imparted via the horn to the part to be welded, whereby the part to be welded is welded,
• a detector for detecting an abnormality in the part to be welded of the workpiece, the detector being disposed further upstream in the conveyance direction of the work piece than the support device, and
• a protective device for prohibiting the welding machine from welding the part to be welded of the workpiece in which the abnormality is detected by the detector.