To provide a bearing device for a wheel in which an air-tightness at a fitted part between a protection cover and an external member is increased to protect a magnetic encoder, rigidity of the protection cover is increased to restrict its deformation and reliability in detection of a rotational speed is improved.

A protection cover 10 comprises a fitting part 10a press fitted into an inner peripheral surface 2d at the end part of an external member 2, a shielding part 10c extending from the fitting part 10a in a diametrical direction through a reduced diameter part 10b of stepped shape and approaching or abutting to a rotational speed sensor arranged near its side surface and a bottom part 10e for closing the end part of an inner member 1 from the shielding part 10c through a stepped part 10d, wherein a seal member 15 is integrally connected to the outer peripheral part of the reduced diameter part 10b, the seal member 15 comprises an annular part 15b formed into a slightly smaller diameter than an outer diameter of the fitting part 10a and a protrusion part 15a formed into a slightly larger diameter than an outer diameter of the fitting part 10a, and the protrusion part 15a is press fitted to an inner peripheral surface 2d at the end part of the external member 2 with a predetermined interference.

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