To provide a bearing structure in which the processing is easy, and the manufacturing cost can be reduced.A bearing structure 1 includes a housing comprising a first housing portion 13 having a cross-sectionally generally-semicircular concave portion and a second housing portion 14 having a cross-sectionally generally-semicircular concave portion forming together with the concave portion 13a of the first housing portion 13 a cross-sectionally generally-circular support hole 16, and a two-division rolling bearing 2 comprising a pair of two-division outer rings 3a, 3b mounted within the support hole 16 of the housing in closely-contacted relation thereto, a plurality of rolling elements 4 so mounted as to be able to roll on inner side surfaces of the two two-division outer rings 3a, 3b, and a pair of two-division cages 5a, 5b holding the rolling elements 4 such that the rolling elements are arranged at generally equal intervals in a circumferential direction, a shaft 12 being internally fitted to the two-division rolling bearing. A bore diameter of the support hole 16 in a direction of mating surfaces of the housing portions is made larger than its bore diameter in a direction shifted 90° from the direction of the mating surfaces.