The lifting/lowering device (100) includes: a first plate member (51); a second plate member (52) to which the first plate member (51) is rotatably connected; a first expansion and contraction bag (31) which is disposed between the first plate member (51) and the second plate member (52) and is capable of expanding and contracting by gas supply and exhaust; a third plate member (53) to which the second plate member (52) is rotatably connected; a second expansion and contraction bag which is disposed between the second plate member (52) and the third plate member (53) and is capable of expanding and contracting by gas supply and exhaust. The first plate member (51), the first expansion and contraction bag (31), the second plate member (52), the second expansion and contraction bag (32) and the third plate member (53) are disposed so as to overlap in a plan view.