To stabilize the posture of the running rapier head by preventing unstable movements of the rapier band in the warp and upward directions during the running of the rapier band and to prevent occurrence of partial wear due to partial load on the guide surface of the rapier band while preventing the weft from inadvertently slipping into the guide groove of the guide member on the reed side and to prevent otherwise eventual erroneous insertion of the weft to thereby stabilize the weaving operation.

In the weft insertion mechanism of a rapier weaving machine wherein an elastic rapier band 3 fitted with a rapier head 6 at the tip is guided in a reciprocating manner by a guide means provided on a sleigh 1 in such a manner as to slidably contact with the faces on both sides and the top and the bottom faces of the rapier band 3 and the end of the weft held by a weft holding member 61 which in turn is provided on the rapier head is conveyed in the direction of the weft insertion, the rapier head 6 is so structured as to position the weft holding member 61 at a location which is closer to the reed side than the side end of the rapier band on the reed side and a guide means 7 is provided on the sleigh 7 to pivotally support the bottom face of the rapier head 6 at a location closer to the reed than the end of the rapier band on the reed side.