PURPOSE: To extremely simplify the supporting method of a motor mounting frame by a method wherein the motor mounting frame is supported within a main body case by being pinched with respective spiral casings for a suction fan and for an exhaust fan in the combined suction-exhaust ventilating fan, which ventilates with suction flow and with exhaust flow at the same time.

CONSTITUTION: Firstly, a motor 20 of double-ended shaft structure and a geared motor 21 are mounted on the motor mounting frame 17. Secondly, a first fan 21 is mounted at the shorter shaft end of the motor 20. Thirdly, the first spiral casing 16 is placed on an intermediate casing 18 in such a manner as to pinch the motor mounting frame 17 between the casings 16 and 18. Fouthly, after that, a second spiral casing 19 is placed under the intermediate casing 18. Fifthly, thenceforth, a second fan 22 is mounted at the longer shaft end of the motor 20. In this case, the mounting directions of the first and second fans 21 and 22 are reverse to each other. Finally, the assembly piled up with respective parts pinched therebetween as described above, is housed in a main body casing 1b through the opening 30 of the main body casing 1b in order to complete the main body casing 1b side.