To provide a supporting structure of a bearing capable of successfully supporting a bearing on a knuckle, and making the supporting structure which is light-weighted and inexpensive.

The supporting structure of the bearing is provided with a bearing bush 10 of double structure comprising a male bush 10A to support the bearing 20, and a female bush 10B fitted into the male bush 10A and retained in a bearing support 2, and a fastening means 30 to fasten the bearing bush 10 in the bearing support 2. The bearing bush 10 is formed in such a tapered shape that male and femal fitting parts 14a, 14b of both the bushes 10A, 10B fitting inside and outside are fitted in the fastening direction by the fastening means 30.