A double-deck elevator capable of adjusting the spacing in the vertical direction between upper and lower cages (20,30) provided on a cage frame in a vertically movable manner, comprising: a screw shaft rotatably supported by said cage frame and extending in the vertical direction; screw shaft driving unit for rotating said screw shaft in the forward and reverse directions; controllers for controlling the operation of said screw shaft driving units; an upper supporting beam which is configured as a cantilever beam engaged at a proximal end thereof with an upper screw part of said screw shaft and vertically moved by the rotation of said screw shaft, and which hoists and supports said upper cage via one upper support arm disposed on an upper part of said upper cage; a lower supporting beam which is configured as a cantilever beam engaged at a proximal end thereof with a lower screw part threaded in a direction opposite to that of said upper screw part of said screw shaft and vertically moved by the rotation of said screw shaft, and which hoists and supports said lower cage via one lower support arm disposed on an upper part of said lower cage; an upper measuring unit which is interposed between said upper support arm connected to an upper part of said upper cage and a distal end of the upper supporting beam, and which measures a load on said upper supporting beam from said upper support arm; and a lower measuring unit which is interposed between said lower support arm connected to an upper part of said lower cage and a distal end of the lower supporting beam, and which measures a load on said lower supporting beam from said lower support arm, wherein said controllers control the operation of said screw shaft driving units based on the load value obtained by said upper measuring unit and the load value obtained from said lower measuring unit before adjusting the spacing in the vertical direction between said upper cage and said lower cage so that said screw shaft driving units output a drive torque with a direction and magnitude for cancelling the rotational biasing force applied to said screw shaft attributable to the difference in weight between said upper cage and said lower cage. a screw shaft rotatably supported by said cage frame and extending in the vertical direction; screw shaft driving unit for rotating said screw shaft in the forward and reverse directions; controllers for controlling the operation of said screw shaft driving units; an upper supporting beam which is configured as a cantilever beam engaged at a proximal end thereof with an upper screw part of said screw shaft and vertically moved by the rotation of said screw shaft, and which hoists and supports said upper cage via one upper support arm disposed on an upper part of said upper cage; a lower supporting beam which is configured as a cantilever beam engaged at a proximal end thereof with a lower screw part threaded in a direction opposite to that of said upper screw part of said screw shaft and vertically moved by the rotation of said screw shaft, and which hoists and supports said lower cage via one lower support arm disposed on an upper part of said lower cage; an upper measuring unit which is interposed between said upper support arm connected to an upper part of said upper cage and a distal end of the upper supporting beam, and which measures a load on said upper supporting beam from said upper support arm; and a lower measuring unit which is interposed between said lower support arm connected to an upper part of said lower cage and a distal end of the lower supporting beam, and which measures a load on said lower supporting beam from said lower support arm, wherein said controllers control the operation of said screw shaft driving units based on the load value obtained by said upper measuring unit and the load value obtained from said lower measuring unit before adjusting the spacing in the vertical direction between said upper cage and said lower cage so that said screw shaft driving units output a drive torque with a direction and magnitude for cancelling the rotational biasing force applied to said screw shaft attributable to the difference in weight between said upper cage and said lower cage.