PURPOSE: To continuously and stably produce a flush-spun net fiber, by blocking the inlet of a heated dissolution section of a screw extruder with a melted polymer, adding a solvent to the melted polymer, mixing both the melted polymer and the solvent to give a soln. and then flush-spinning the soln.

CONSTITUTION: A polymer is melted in an extruder 11 and then sent to a polymer dissolving section blocked with the melted polymer in a barrel 10. A solvent is sent using a solvent pump 13 into the polymer-dissolving section through a check valve. Subsequently, the solvent and the polymer are mixed by a screw to give a soln., which is sent into a spinning apparatus 14 in the soln. state. The polymer soln. is extruded from a spinning orifice of the spinning apparatus 14 into a low pressure section.