PURPOSE: To automatize sliver joining formerly remained as a hand work among automatizations of spinning processes by flatly spreading each end part of two pieces of sliver, superposing in an opposite state, interlacing fibers applied of transversely reciprocating nip pressure with each other and making a cross section to a circular shape.

CONSTITUTION: For instance, two slivers having flatly spread end parts obtained by passing through two rollers 2 and 3 individually having grooves 1 obliquely cut from a central part to end parts in the surface are superposed in an opposite state and resultant superposed part of the sliver is pressed by a narrowing gap between the two rollers to a fixed value, then transversely reciprocating nip pressure is applied to the sliver with a pressing part material composed of a pair of board materials in which at least one of the board materials are able to be reciprocated in a transverse direction of the sliver, thus said pressing force is released and the sliver is drawn to a spinning machine, then width of the sliver is returned to initial value by said drawing tension, thus a cross section is made to circular and the sliver joining process is completed.