[Problem]To provide a bonding device in which a capillary can perform stable vibration from a low frequency to a high frequency while achieving lightening and downsizing of a load to be driven by a piezoelectric element and in which stable vibration can be transmitted to the capillary without disturbing operation of expansion and contraction of the piezoelectric element as keeping preliminary pressure to the capillary constant.[Solution]The bonding device is provided with a vibration driving portion (7), the vibration driving portion (7) including a piezoelectric element (10) that is expanded and contracted along an axial direction of a bonding arm (3) with one end thereof fixed to a leading end of the bonding arm (3), a capillary holding portion (15) that is in contact with a circumferential face of a capillary (20) at a base end side thereof as being fixed to the other end of the piezoelectric element (10), a string-like member (23) that is wound to a half circumferential face of the capillary (20) at the base end side on a side opposite to the capillary holding portion (15), and a tension mechanism (25) that is arranged at the bonding arm (3) side to press and hold the capillary (20) to the capillary holding portion (15) by exerting tensile force on the string-like member (23).