PURPOSE: To improve the operability of a ventilator by a method wherein an operating knob is moved to regulate the direction of air flow into up-and-down and left-and-right freely while light is emitted from a light source, provided on the operating knob.

CONSTITUTION: A plurality of horizontal louvers 25, moved in conjunction with each other, and a plurality of vertical louvers 31, moved in conjunction with each other, are supported at an air outlet port for a ventilating passage 12. An operating knob 55 is engaged with a first louver 35 positioned at the center of the horizontal louver 25 movably. A contact point body 143 and a lead wire 44 are accommodated in the first louver 35 while slidingly contacting parts 46a, 47a are provided projectingly on the upper surface 35a and the lower surface 35b of the first louver 35 respectively. Electroconductive plates 76, 77, contacted with the slidingly contacting parts 46a, 47a, are attached to the upper and lower surfaces of the louver engaging part 66 of the operating knob 55. LEDs 711 are connected to these electroconductive plates 76, 77. The direction of air flow can be regulated freely into up-and-down and left-and- right directions freely by moving the operating knob 55 while the position of the operating knob 55 can be confirmed easily even at night by emitting light from a light source 74 provided on the operating knob 55 whereby the operability of a ventilator can be improved.