A separator for use in a linear guide having a guide rail, a slider disposed on the guide rail so as to move relatively each other, and a plurality of roller-shaped rolling elements incorporated in the slider, the separator has a separator main body having, on both sides in a front and rear direction thereof, recessed surface sections which contact circumferential sections of the rolling elements; and at least a pair of arm sections provided parallel to each other on both sides of the separator main body while being oriented in the same direction, wherein a length of the arm section is equal or shorter than a distance between centers of two adjacent rolling elements with the separator main body sandwiched therebetween, with respect to a lateral direction of the separator main-body.