Work carrier device and attitude holding method of work carrier device controller for work carrying apparatus

To control the position of a workpiece while restraining enlargement and increase of weight. To move a work WK linearly along a horizontal line, by preventing the moving trajectory of the work from changing into a curve deflected in its self-weight direction when carrying the work by a carrying robot to the carry-in port of a load locking chamber. Deflection of arms A1, A2 is restrained by applying tensile force to belts 6, 9 wound between pulleys 5, 8 provided on head end parts of the arms A1, A2 and pulleys 4, 7 provided on base end parts through idler rollers 11, 21 and tension rollers 12, 22. A vertical-deflection quantity Z of an arm is set by making it correspond to a horizontal-movement quantity X of the tip of the arm. Then, a vertical-deflection quantity Z12 corresponding to a present horizontal- movement quantity X12 (P12) of the tip of the arm is determined from the set content in the above. Accordingly, a vertical-movement quantity Z (vertical drive command) is so corrected that the arm is moved by the above deflection quantity Z12 in the opposite vertical direction to its deflection direction, and the vertically drive command is output.