Four-point ball bearing includes an inner ring and an outer ring defining raceway grooves. The raceway grooves are constituted by two circular arcs different in curvature provided on opposite sides of a widthwise center of the raceway groove. A plurality of balls is arranged between the inner and outer rings so that the balls can roll. Their contact angles are usually 35° large. The bearings are capable of transmitting high axial loads in both the directions.