An operation switch is arranged in a manner that switch knobs 1 and 2 each for selecting one of related plural functions is provided, and a display portion for displaying the one of related plural functions selected by the corresponding switch knob is provided for each of the switch knobs 1 and 2. Thus, when the switch knob 1 or 2 is operated, the desired function relating to the switch knob 1 or 2 thus operated can be selected among the plural functions for adjusting the blowing direction and an air flow rate and also the selected function can be displayed at the switch knob 1 or 2 thus operated.