A stage device to be used in a vacuum, comprising: a gas supply unit configured to generate a gas; a square shank (71, 91 c, 91 e, 92a) having four of upper, lower, right, and left surfaces; a slider (72, 91d, 91f, 92b) formed in a frame shape surrounding the square shank (71, 91c, 91e, 92a) and having surfaces facing the respective four surfaces of the square shank (71, 91c, 91 e, 92a), and disposed to be movable; and an air bearing configured to float the slider (72, 91d, 91f, 92b) by supplying the gas to a space between the square shank (71, 91c, 91e, 92a) and the slider (72, 91d, 91f, 92b), wherein the slider includes an air chamber provided on the surfaces facing the square shank (71, 91c, 91 e, 92a) and configured to accumulate air; and the square shank (71, 91c, 91e, 92a) includes thereinside a slider-moving air flow passage (76a-76f) configured to supply the gas from an inlet port (74a, 74b) for letting in the gas generated by the gas supply unit to an outlet port (76g-76j) for supplying the gas to the air chamber of the slider (72, 91d, 91f, 92b), characterized in that the slider further includes an air pad configured to emit the air for floating the slider (72, 91d, 91f, 92b) above the square shank (71, 91c, 91 e, 92a), and an air supply groove configured to supply the air to the air pad, and the square shank (71, 91c, 91 e, 92a) includes an air flow passage for air pad configured to connect a supply port for supplying the air generated by the gas supply unit to an air outlet port for infusing the air into the air supply groove, the infused air is supplied to the air pad of the slider (72, 91d, 91f, 92b) through piping inside the slider (72, 91d, 91f, 92b). a gas supply unit configured to generate a gas; a square shank (71, 91 c, 91 e, 92a) having four of upper, lower, right, and left surfaces; a slider (72, 91d, 91f, 92b) formed in a frame shape surrounding the square shank (71, 91c, 91e, 92a) and having surfaces facing the respective four surfaces of the square shank (71, 91c, 91 e, 92a), and disposed to be movable; and an air bearing configured to float the slider (72, 91d, 91f, 92b) by supplying the gas to a space between the square shank (71, 91c, 91e, 92a) and the slider (72, 91d, 91f, 92b), wherein the slider includes an air chamber provided on the surfaces facing the square shank (71, 91c, 91 e, 92a) and configured to accumulate air; and the square shank (71, 91c, 91e, 92a) includes thereinside a slider-moving air flow passage (76a-76f) configured to supply the gas from an inlet port (74a, 74b) for letting in the gas generated by the gas supply unit to an outlet port (76g-76j) for supplying the gas to the air chamber of the slider (72, 91d, 91f, 92b), characterized in that the slider further includes an air pad configured to emit the air for floating the slider (72, 91d, 91f, 92b) above the square shank (71, 91c, 91 e, 92a), and an air supply groove configured to supply the air to the air pad, and the square shank (71, 91c, 91 e, 92a) includes an air flow passage for air pad configured to connect a supply port for supplying the air generated by the gas supply unit to an air outlet port for infusing the air into the air supply groove, the infused air is supplied to the air pad of the slider (72, 91d, 91f, 92b) through piping inside the slider (72, 91d, 91f, 92b).