1. An electric motor comprising:a stator;
a rotor including a rotating shaft rotatable about an axis with respect to the stator;
a bearing configured to rotatably support the rotating shaft;
a housing configured to support the bearing and define a space adjacent to the bearing on an outer side in a direction of the axis; and
a terminal box for a power line connected to the electric motor,
wherein an inner portion of the terminal box is in fluid communication with a clean environment, the inner portion of the terminal box and the space communicate with each other through a hollow tube provided on an outer side of the stator, and air in the clean environment automatically flows into the space through the inner portion of the terminal box and the hollow tube in accordance with a rotation of the rotor so that air, flowing out from a gap that is adjacent to the bearing and communicated with an outer portion of the electric motor, is compensated;
wherein an element other than the hollow tube does not intervene between the terminal box and the space defined by the housing.