To provide a disconnected thread processing device capable of smooth and quick disconnection treatment almost without accumulation of lines of thread in a spinning cylinder upon occurrence of disconnection, when multi-filament lines of thread formed of a thermoplastic synthetic fiber, for example with a size of a single fiber of 2 dtex or less is melt-spun, or cospun.

This disconnected thread processing device is installed to a thread melt-spinning device having at least an oil agent giving means (7) installed in thread spinning cylinders (3), (5) cooling a plurality of multi-filament lines of thread (Y) formed of a spun thermoplastic synthetic fiber. The disconnected thread treatment device comprises a disconnected thread detecting means detecting disconnection of the line of thread (Y), and thread removing means (12), (13), (14) and (15) for separating the traveling lines of thread (Y) from the oil agent giving means (7) by disconnected thread detection signals from the disconnected thread detection means. The device also comprises a thread line suction means (8) downstream of the oil agent giving means (7), a thread line cutting means (9) installed immediately below the thread line suction means (8), and thread line collecting means (10) and (11) collecting a plurality of the lines of thread (Y) to a thread line suckable position of the thread line suction means (8) along a thread line traveling direction in this order.