A motion guide device includes a rolling passage formed between two members, a number of cylindrical roller bearing members disposed in the rolling passage and engaged between the members, and a number of spacers disposed in the rolling passage and engaged between the cylindrical roller bearing members, the spacers each include two opposite curved depressions for engaging with the cylindrical outer peripheral surfaces of the cylindrical roller bearing members, and each defined by a planar middle surface, a tilted upper surface and a tilted lower surface inclined relative to the planar middle surface and the vertical axis (Z) of the spacer for selectively engaging with the cylindrical roller bearing members.