Abstract: A wire bonder is frequently used for assembling the electronic parts of a semiconductor device or the like and exhibits an effect in the electric connections of the aforementioned electronic parts with a fine metal wire. The wire bonder according to the present invention comprises a clamper for clamping a bonding wire, and bonding wire disconnection detecting means for detecting the disconnection of the bonding wire in terms of the wire clamping state of the clamper. In order to detect highly accurately and reliably the disconnection of the bonding wire, the aforementioned bonding wire disconnection detecting means is characterized by the provision of a detecting unit for detecting a quantity which corresponds to the facing gap of the clamper during the clamping operation.