To enhance a load capacity by allowing an axial load in both directions and causing a contact with a track surface into a line contact by making as a basic shape a simple shape formed by combining a rolling element shape with a cone shape.

The rolling elements 11 for a bearing is configured so that there is formed in symmetrical shape a cone portion 14 which has on both sides of reference surface 13 containing reference line perpendicularly intersecting with turning center axis 12 at the center, a tapered surface whereinthe diameter becomes smaller as the distance from the center becomes longer. Additionally, a column portion whose diameter is identical to that of the bottom surface of the cone portion 14 with the turning axis 12 as the center is formed and the cone portion 14 is integrally formed on both ends surface of the column portion, respectively.