Abstract: An air-floating guide rail device includes a guide rail unit, a slider unit, and a linear motor unit. The guide rail unit includes a guide rail body and two air-floating block sets made of a material different from that of the guide rail body and each including top and side air-floating blocks. The slider unit includes a main sliding seat and two lateral sliding seats connected integrally to the main sliding seat and each having first and second guiding surfaces transverse to each other and disposed respectively adjacent to corresponding top and side air-floating blocks, and first and second air guiding passages connecting the first and second guiding surfaces to the external environment. The linear motor unit includes a stator and a mover mounted fixedly to the main sliding seat and movable relative to the stator for driving linear movement of the slider unit relative to the guide rail unit.