A dehydration device that removes moisture from a process gas that contains the moisture and is compressed by a compressor, the dehydration device comprising: an absorption unit configured to remove the moisture from the process gas by bringing the process gas into contact with a dehydration solvent to cause the dehydration solvent to absorb the moisture; a first pressure detecting unit configured to detect a pressure inside the absorption unit; a still unit configured to separate the moisture from the dehydration solvent by heating the dehydration solvent that absorbed the moisture at the absorption unit; a carrying line (L 21, L 22, L 23) configured to carry the dehydration solvent from the absorption unit to the still unit; a conveying pump disposed in the carrying line (L 21, L 22, L 23) and configured to suck in the dehydration solvent conveyed from the absorption unit and eject the dehydration solvent toward the still unit; a first bypass line (L 25) coupling the carrying line (L 21, L 22, L 23) upstream of the conveying pump and the carrying line (L 21, L 22, L 23) downstream of the conveying pump; a first on-off valve disposed in the first bypass line (L 25); and a control unit configured to control the conveying pump and the first on-off valve; characterized in that in a case where a pressure detected by the first pressure detecting unit is lower than a first predetermined pressure, the control unit closes the first on-off valve and causes the conveying pump to operate, and in a case where the pressure detected by the first pressure detecting unit is equal to or higher than the first predetermined pressure, the control unit opens the first on-off valve and causes the conveying pump to stop. an absorption unit configured to remove the moisture from the process gas by bringing the process gas into contact with a dehydration solvent to cause the dehydration solvent to absorb the moisture; a first pressure detecting unit configured to detect a pressure inside the absorption unit; a still unit configured to separate the moisture from the dehydration solvent by heating the dehydration solvent that absorbed the moisture at the absorption unit; a carrying line (L 21, L 22, L 23) configured to carry the dehydration solvent from the absorption unit to the still unit; a conveying pump disposed in the carrying line (L 21, L 22, L 23) and configured to suck in the dehydration solvent conveyed from the absorption unit and eject the dehydration solvent toward the still unit; a first bypass line (L 25) coupling the carrying line (L 21, L 22, L 23) upstream of the conveying pump and the carrying line (L 21, L 22, L 23) downstream of the conveying pump; a first on-off valve disposed in the first bypass line (L 25); and a control unit configured to control the conveying pump and the first on-off valve; characterized in that in a case where a pressure detected by the first pressure detecting unit is lower than a first predetermined pressure, the control unit closes the first on-off valve and causes the conveying pump to operate, and in a case where the pressure detected by the first pressure detecting unit is equal to or higher than the first predetermined pressure, the control unit opens the first on-off valve and causes the conveying pump to stop.