An exhausting apparatus of a motor assembly comprises a motor assembly generating a suction force and having an air outlet; a motor housing enclosing the motor assembly and having an air discharging opening for exhausting air via the air outlet; and a porous noise prevention board configured in the exhausting passage formed by the motor housing. The motor housing has a porous noise prevention part at least at a portion, and at least a part of air discharging from the air outlet passes through the noise prevention part. As such, a noise can be reduced when air is discharged.