To provide a bearing unit for wheel that can prevent the invasion of rain water, dust and the like and the leakage of differential oil while reducing the weight and downsizing.

The bearning is equipped with a hub wheel 1 having a flange 6 for setting a wheel integrally in one end and forming a cylindrical small-sized step part 7 that is extended axially on outer circumference and a serration 8 engaging to a drive shaft D/S on an inner circumference, an inward member 3 that is pressed in small-sized step part 7 and consists of one pair of inner rings 10 forming an inner rolling face 10a on outer circumference, an outward member 4 that has a setting flange 4b to a car body fixed to wheel shaft pipe N that a double row outer rolling face 4a facing the inner rolling face 10a is formed to inner circumference, a double row rolling mover 5 accommodated between both rolling faces of the outward member 4 and the inward member 3, a retainer 11 to retain these rolling movers to the rolling movement free and a seal 12 that tightly seals the annular space of the inward member 3 and the outward member 4, and a bulkhead 9 is formed integrally to block up the inner diameter part in the outboard side end part of the hub wheel 1.