To provide technology for reducing sliding resistance between each rolling element and the contact surface of the inner peripheral face of each pocket.

A cage 3 is used for a linear motion device which comprises a guide rail extending in a predetermined direction, a slider movable along the guide rail, and the plurality of rolling elements 4 arranged to freely roll while rotating between the guide rail and the slider with the movement of the slider. The cage has the plurality of pockets arranged between the guide rail and the slider and formed with their inner peripheral faces for rotatably holding the individual rolling elements. The inner peripheral face of each pocket partially contacts a rolling face 4S of the rolling element.