To prevent defective weaving while avoiding the increase in the overall size of a compressed air supplying apparatus installed one for each jet loom.

This compressed air supplying apparatus 15 is composed of a supplymng flow rate-determining circuit 16, an inverter 17 constituting a supplying flow rate-switching means, a pulse motor 18 constituting the supplying flow rate switching means, a fixed volume compressor 19 and a pressure switch 20. The supplying flow rate determining circuit 16 controls the rotational speed of the pulse motor 18 based on the pressure detected by the pressure switch 20 and the ON-OFF state of a starting switch 13 reflecting the weaving state of the jet loom. The rotational speed of the compressor 19 is changed to an interruption mode according to the turning ON of the start switch 13 to increase the flow rate of the compressed air over a prescribed period at the start of weaving with the jet loom compared with the supplying flow rate of the compressed air during the weaving operation.