The invention relates to an oil-storing device used in bearing assembly in a kind of motor including a rotor of motor and a stator of motor; the rotor includes a rotation shaft housing holding a shaft, many impellers which are settled in radial direction at proper interval along outer circumference the rotation shaft housing, magnets which are settled on the back of the rotation shaft housing; the stator includes a frame, a circular bearing receptacle shaped inside the frame, a stator subassembly and a stator subassembly base; an oil-impregnated bearing is settled inside the circular bearing receptacle; it is characterized by a nether bearing part and an upper bearing part which is joined vis-à-vis in the orientation of the rotation shaft; a hole in the nether bearing part and the upper bearing part for the rotation shaft; a concave shaped in the interlayer of the upper part and nether part of the oil-impregnated bearing respectively; an oil-storing device which is formed by the joining of the concave of the nether bearing part and the upper bearing part. An upper bearing part and a nether bearing part are arranged in the orientation of the rotation shaft according to the invention So that it is not only easy to manufacture but also easy to change the size of the concave, namely, the capacity of oil-storing, so it's useful very much.