In a vacuuming motor used by being attached to a peripheral edge of a motor attaching hole provided at a vacuum chamber, an end portion on a load side of a motor main body is attached with a reduction gear main body having an attaching flange fixed to the motor attaching hole to interpose an O-ring therebetween and the attaching flange is fixed with vacuum seals and constituted by a resin and brought into contact with an output shaft of the reduction gear main body for partitioning an inner space of the reduction gear main body and the motor main body and an inner space of the vacuum chamber.