To provide a pneumatic operation device capable of supplying compression air of a normal pressure to pneumatic equipment even when the pressure of the compression air circulating through a compressed air line in a plant is lower than the normal pressure, and normally operating the pneumatic equipment, and to provide a reduced-pressure drying apparatus including the pneumatic operation device.

Compressed air circulating through a compression air line L is supplied to air cylinders 4, 15, 27, 30, 41, 44 that use an air pressure through a compressed air flow channel 52 and circulation pipes 65A, 65B, 67A, 67B, 69A, 69B, 71A, 71B, 73A, 73B, 75A, 75B. A buffer tank 84 is interposed in the compressed air flow channel 52. Further, a stop valve 83 for blocking the circulation of the compressed air to the compressed air line L side from the buffer tank 84 side is interposed more in the compressed air line L side from the buffer tank 84 on the compressed air flow channel 52.