An insulated bearing includes a pair of bearing rings arranged concentrically to each other and rolling elements arranged to be rotatable between the pair of bearing rings, at least one of the bearing rings having an insulating layer formed thereon. The one of the bearing rings having the insulating layer formed thereon has an annular groove having an arc-shaped cross section formed on each of both end surfaces of the bearing ring. At least a surface from a non-raceway surface side circumferential surface to the annular groove of the bearing ring is covered by the insulating layer. The insulating layer is a ceramic thermal sprayed layer.