PURPOSE: To ensure the end of a foil yarn to be guided to a detection switch for foil yarn alignment by holding in a vertically movable way a bent guide bar with a slope on a frame set under the end of the moving channel of a foiling rod so as to cross said moving channel.

CONSTITUTION: A detection switch 40 for foil yarn alignment is installed on the upper part of a fitting plate 42 raised from a frame 10 set under the end of the moving channel of a foiling rod, and a guide channel 44 is formed at the center of the upper end of the fitting plate. The upper table 13 of a guide bar holder 11 is provided with a vertically penetrated hole 14 and a guide channel 15, each side plate 12 with a longitudinal guide channel 17, and a guide bar frame 20 having a bent guide bar 23 is held so as to be vertically movable through the vertical hole 14. The frame 20 is checked with an operational head 32 at the tip of the operating shaft 31 for a solenoid 30.