To provide an angular contact ball bearing device capable of avoiding excessive pre-load of bearings in two rows on an inner side at operation time without changing amount of pre-load of the whole bearing device when assembling it.

This angular contact ball bearing device is constituted by arranging bearings 4A to 4D in four rows and arranging the bearings 4B, 4C in two rows on the inner side by matching them on a rear surface and the bearings 4A, 4D in two rows on an outer side whose contact angle is in the same direction as that of adjacent bearings 4B, 4C on the inner side. Amount of pre-load of the bearings 4B, 4C in two rows on the inner side is set to be smaller than amount of pre-load of the bearings 4A, 4D in two rows on the outer side.