A wheel bearing apparatus for a vehicle comprising: an outer member formed on its outer circumference with a body mounting flange to be mounted on a knuckle and on its inner circumference with double row outer raceway surfaces (5a, 5a); an inner member including a hub wheel and an inner ring, the hub wheel being formed on its one end with a wheel mounting flange for mounting a wheel and having a cylindrical portion axially extending from the wheel mounting flange, and the inner ring being press-fitted to the cylindrical portion of the hub wheel, the inner member being formed on its outer circumference with double row inner raceway surfaces (1a, 2a) opposing to the double row outer raceway surfaces (5a, 5a); double row rolling elements (4, 4) freely rollably contained between the outer raceway surfaces (5a, 5a) of the outer member and the inner raceway surfaces (1a, 2a) of the inner member; and seals (8, 9) mounted within annular openings formed between the outer member and the inner member; wherein the outer-side seal of the seals (8, 9) comprises a core metal (12, 17, 20) and a sealing member (13, 18, 21, 29); the core metal (12, 17, 20) including a cylindrical portion press-fitted into the outer-side end inner circumference of the outer member a radially inner portion bent and extending radially inward from the cylindrical portion, and a disc portion extending radially outward from the cylindrical portion and adapted to be closely contacted to the outer-side end face of the outer member; and the sealing member (13, 18, 21, 29) being integrally adhered via vulcanized adhesion to the radially inner portion of the core metal (12, 17, 20); wherein the sealing member (13, 18, 21, 29) comprises an integrally formed side lip inclined radially outward and adapted to be slidably contacted to the inner-side base portion of the wheel mounting flange via an axial interference, and a weir portion (13d, 18a, 22, 30, 31, 32, 33) formed around the outer circumference of the disc portion of the core metal (12, 17, 20) so as to cover the disc portion and be adhered thereto, the weir portion (13d, 18a, 22, 30, 31, 32, 33) being formed so that it is projected radially outward from the outer circumference of the outer-side end of the outer member (5, 5') and elastically contacted thereto characterized in: that the outer circumference of the outer-side end of the outer member (5, 5') is formed as a smooth and smaller diameter portion by a machining process to which the inner circumference of the weir portion (13d, 18a, 22, 30, 31, 32, 33) of the sealing member (13, 18, 21, 29) is elastically contacted. an outer member formed on its outer circumference with a body mounting flange to be mounted on a knuckle and on its inner circumference with double row outer raceway surfaces (5a, 5a); an inner member including a hub wheel and an inner ring, the hub wheel being formed on its one end with a wheel mounting flange for mounting a wheel and having a cylindrical portion axially extending from the wheel mounting flange, and the inner ring being press-fitted to the cylindrical portion of the hub wheel, the inner member being formed on its outer circumference with double row inner raceway surfaces (1a, 2a) opposing to the double row outer raceway surfaces (5a, 5a); double row rolling elements (4, 4) freely rollably contained between the outer raceway surfaces (5a, 5a) of the outer member and the inner raceway surfaces (1a, 2a) of the inner member; and seals (8, 9) mounted within annular openings formed between the outer member and the inner member; wherein the outer-side seal of the seals (8, 9) comprises a core metal (12, 17, 20) and a sealing member (13, 18, 21, 29); the core metal (12, 17, 20) including a cylindrical portion press-fitted into the outer-side end inner circumference of the outer member a radially inner portion bent and extending radially inward from the cylindrical portion, and a disc portion extending radially outward from the cylindrical portion and adapted to be closely contacted to the outer-side end face of the outer member; and the sealing member (13, 18, 21, 29) being integrally adhered via vulcanized adhesion to the radially inner portion of the core metal (12, 17, 20); wherein the sealing member (13, 18, 21, 29) comprises an integrally formed side lip inclined radially outward and adapted to be slidably contacted to the inner-side base portion of the wheel mounting flange via an axial interference, and a weir portion (13d, 18a, 22, 30, 31, 32, 33) formed around the outer circumference of the disc portion of the core metal (12, 17, 20) so as to cover the disc portion and be adhered thereto, the weir portion (13d, 18a, 22, 30, 31, 32, 33) being formed so that it is projected radially outward from the outer circumference of the outer-side end of the outer member (5, 5') and elastically contacted thereto characterized in: that the outer circumference of the outer-side end of the outer member (5, 5') is formed as a smooth and smaller diameter portion by a machining process to which the inner circumference of the weir portion (13d, 18a, 22, 30, 31, 32, 33) of the sealing member (13, 18, 21, 29) is elastically contacted.