A wheel bearing has a seal device formed as a pack seal with an annular sealing plate and slinger. The sealing plate has a metal core and an integrally adhered sealing member. The sealing member has a base portion, side lip and radial lip. The base portion covers an inner circumferential surface of the metal core. The radial lip slidingly contacts the cylindrical portion of the slinger. A garter spring is mounted on the radial lip. A tightening force of the garter spring is set to 50% or more of a total tightening force of the radial lip. The tightening force of the radial lip without the garter spring is set to 3N or more.