Drive device and electric power steering apparatus

A drive device that outputs a drive force, which assists a steering operation of a driver of a vehicle by rotating a worm that is meshed with a worm wheel installed to a drive force transmission shaft for transmitting a steering force of the driver to a steerable wheel of the vehicle, the drive device comprising:

• a stator;
• a rotor that is rotatably placed on a radially inner side of the stator;
• a rotatable shaft that is rotatable integrally with the rotor and is connectable with one axial end part of the worm;
• a case that receives the stator and the rotor;
• a bearing box that is placed on an opposite side of the case, which is opposite from the worm;
• a bearing that is received in the bearing box and rotatably supports an end part of the rotatable shaft, which is opposite from the worm;
• and
• a resilient member that is in a form of a ring and is placed between an inner wall of the bearing box and an outer race of the bearing, wherein:
• a radial direction of the rotatable shaft, along which the worm and the worm wheel are placed one after another, is defined as an X-direction, and another radial direction of the rotatable shaft, which is perpendicular to the X-direction, is defined as a Y-direction;
• and
• a distance, which is measured along the Y-direction between two opposed parts of the inner wall of the bearing box that are opposed to each other along the Y-direction, is larger than a distance, which is measured along the X-direction between two opposed parts of the inner wall of the bearing box, which are opposed to each other along the X-direction.