PURPOSE: To facilitate an installation of an air blower by a method wherein rails are fixed within through-pass holes formed at a side wall, an air blower having rotating rollers is mounted on the rails and moved to be connected to a discharging duct and further the air blower is fixed to the side wall.

CONSTITUTION: A car port side wall 1 is formed with a through-pass hole 2. A pair of rails 3 are removably attached within the through-pass hole 2. The rails 3 are adjusted by a level adjusting means 5 to occupy a horizontal state and then an air blower 4 having rotating rollers 4C is mounted. Then, the air blower 4 is moved toward the discharging duct 6 arranged outside the device and then a discharging port 4A of the air blower 4 is connected to a joint 7 of a bellows 6A of the duct 6. A frame 4D around a suction port 4B of the air blower 4 is fixed to the side wall 1 with screws 9. With such an arrangement as above, the heavy air blower 4 may easily be moved and its mounting operation can be easily performed, its taking-out operation may also be facilitated and its maintenance work can be efficiently carried out.