The present invention relates to a slider of linear guideway which includes the sliding-block, the end-cup and the ball retainer. The characteristic of this present invention is that the ball retainer doesn't use the screws for firm, therefore can scant the finished cost and the fabricated time. Besides, the ball retainer can provide the force to support between two ends of the ball retainer, thereby can increase the strength of the ball retainer to avoid changing the shape.