A method of repairing a bearing of a wind turbine generator is provided which is able to more permanently repair a gap which occurred between a constituent member of the wind turbine generator and a bearing ring of the bearing. For example, in the case of repairing the gap 13 between the main shaft outer cylinder 10 of the wind turbine generator 1 and the outer ring 12A of the main bearing 12, the plate 40 is inserted between the main shaft outer cylinder 10 and the outer ring 12A, and also the plate 40 is fixed to an inner circumferential surface of the main shaft outer cylinder 10 by the adhesive agent 41. On the other hand, slip is permitted between the plate 40 and the outer ring 12A of the main bearing 12.