Rolling element retainer and endless circulating linear motion apparatus using the same

By reducing as much as possible the bending stress acting on the outer surface of the connection portion, to provide an endless circulating linear motion apparatus using high rolling element retainer and the same durable. Holds the plurality of balls 2 which are arranged at predetermined intervals in series, each ball 2 and the ball holding portion 10 that holds so as to sandwich the front and rear along the ball arrangement direction from the ball holding portion 10 in the ball array direction the wing portions 22 protruding in a direction perpendicular against, a flexible connecting portion 23 for connecting the wing portion 22, provided with, by deformation of the connecting portion 23, a ball while the ball held by the ball holding portion 10 in the rolling element retainer and it is possible to bend the second arrangement direction, the ball array width A1 of the wing portions 22, characterized in that not more than the width A0 ball array direction of the ball holding portion 10.