To provide a wire-feeding mechanism for which general purpose wire can be used and wherein degradation of the wire is reduced.

The wire-feeding mechanism is used for a container for a radiation source in order to feed or wind a wire 61, which contacts a driving roller 43, by means of the driving roller 43. At the tip of the wire, the radiation source 60 is fitted. The wire 61, having a energizing force of extending itself, is wound along a winding surface 31 of a reel 30. A roller chain 45 is arranged around the driving roller 43. By putting the wire 61 between multiple roller links 46 of the chain and the driving roller 43, a driving force is applied to the wire 61 by the driving roller 43.