To provide a portable ventilating operation machine capable of effectively executed while controlling the increase of weight or the increase of the size of an outward form to the minimum under such conditions as ventilating efficiency required for drastic reduction of sounds is ensured.

The said portable ventilating operation machine includes a motor 20 and a ventilating section 30 consisting of a centrifugal front stage blower 31 rotated and driven with an output shaft 25 of the motor 20, the rear stage blower 32 and a joint ventilating passage 50 for connecting them. The front stage blower 31 and rear stage blower 32 are constituted of a double faced fan 40 common to a single body arranging the front stage fan blade 41 and rear stage fan blade 42 to both surfaces of a disk-like main plate 41 monolithically fixing their fans to the output shaft 25 of the motor 20.