A radial gap between an outer circumferential surface of an encoder member joined to an outward flange portion of a slinger and an inner circumferential surface of a seal body includes a first gap portion and a second gap portion closer to an inward flange portion of a core metal than the first gap portion is. The outer circumferential surface that defines the first gap portion is a cylindrical outer circumferential surface, and the radial gap in the first gap portion is substantially constant in an axial direction. The outer circumferential surface that defines the second gap portion is a conical outer circumferential surface reduced in diameter as approaching the inward flange portion of the core metal in the axial direction, and the radial gap in the second gap portion is gradually increased as approaching the inward flange portion of the core metal in the axial direction.