The present invention relates to a bearing device for supporting a pinion shaft so as to freely rotate with respect to a case. The bearing device comprises a first tilt-contact rolling bearing provided on the connecting-flange-side outer peripheral surface of the pinion shaft and a second tilt-contact rolling bearing formed from an angular ball bearing provided on the pinion-gear-side outer peripheral surface of the pinion shaft, wherein lines of action of the first and second tilt-contact rolling bearings intersect with one another on an outer diameter side, the connecting-flange-side end portion of the first tilt-contact rolling bearing and the pinion-gear-side end portion of the second tilt-contact rolling bearing are respectively sealed with seal members, a sealed space between the seal members is infilled with grease, and the connecting flange is fastened in the pinion-gear direction to thereby preload the first and second tilt-contact rolling bearings.