To surely prevent a filament from being doubly wound round a take-up drum and being deviated from the take-up drum in winding the filament round the take-up drum without a stop mechanism for obstacle detection.

A take-up drum 16 is fitted to a main roller 14 mounted to a bracket, a filament 12, both ends of which are fitted to the take-up drum and a suspended member 11, is wound round the take-up drum, and the main roller is rotated by main roller driving means. A filament guide 23 is fitted to a part of a lower cover body 22 covering the lower surfaces of the main roller and the take-up drum where the filament passes. The filament guide includes: a case 31 provided with a long hole 31a for loosely inserting the filament; and a slider 32 provided with a passing hole for inserting the filament and stored in the long hole. Lock means 34 for inhibiting or allowing sliding of a slider according to the size of an angle of projection inclination of the filament to the vertical plane of a locus including a locus of a passing hole when the slider slides is provided between the case and the slider.