Abstract: A bearing structure of the present disclosure includes a rotation shaft, a bearing that is attached in a housing to support the rotation shaft with respect to the housing and includes an inner race through which the rotation shaft is inserted and an outer race which includes an annular groove portion formed on an outer peripheral surface facing an inner wall surface of the housing, and an O-ring which is disposed on the groove portion of the outer race of the bearing, protrudes outward in a radial direction in relation to the outer peripheral surface, and comes into contact with the inner wall surface of the housing. A clearance is formed between the inner wall surface of the housing and the outer peripheral surface of the bearing. The clearance is larger than a radial displacement amount of the O-ring.