To provide a fastening device for simply fastening crossing points of various kinds of wires with the use of wire fasteners.

In a fastening device, a wire fastener 100 stored in a fastener storage part provided in a body casing 1, is discharged through a discharge port by means of a discharge means (actuating lever 51) in response to a forward moving motion of a handle part 70 movably provided in the body casing 1. Further, an elastically deforming part (straight line part 103) is pressed by a pressing part 92 of a pressing member 91 associated with the moving motion of the handle part 70 in such a condition that a first locking part (ring part 102) of the wire fastener 100 is locked to a wire B1 of this side, and accordingly, the elastically deforming part is curved in a U-shape about the first locking part as a center while a second locking part (hook part 104) is locked to a rear wire B2 crossing thereto, thereby the both wires B1, B2 are fastened at their crossing point.