PURPOSE: To provide possibility of setting the length of untwined portion at the ends of thread parts to be spliced always at the optimum value and thereby enhancing the splicing performance, by adjusting the injection point of the pressure air for untwining of thread ends, which is allowed to jet against the thread ends placed in the untwining pipe of a pneumatic splicing device.

CONSTITUTION: This pneumatic type splicer to be used in an automatic winder has a thread-end untwining device and performs splicing of a thread end YP on the package side with a thread end YB on the bobbin side. This untwining device includes a thread-end untwining pipe 61 to be fitted in a nozzle hole 12 of block 50 slidably and rotatably. For untwining, the thread end YB introduced into a splicing hole 4 is sucked by the vacuum force, which acts through a flexible pipe 62, and led into the nozzle hole 12, and then compressed fluid is allowed to jet against the thread end YB from an air conduit 64 and a thin jet hole 63 formed aslant in the pipe 61. Adjustment of the length of untwined portion is made by turning the pipe 61 and displacing vertically the position of opening facing the air conduit 64.