A compression device comprising: a compressor including a casing having a rotor chamber (38; 38d, 38e), a rotor that is housed in the rotor chamber (38; 38d, 38e) inside the casing and configured to compress gas by rotating, a rotor shaft (22a; 22b; 221b, 222b) that extends from the rotor, a bearing that is provided inside the casing and supports the rotor shaft (22a; 22b; 221b, 222b) so that the rotor is rotatable, and a first shaft-sealing part (32; 32a, 32b) that is provided between the rotor chamber (38; 38d, 38e) and the bearing in the casing to seal a periphery of the rotor shaft (22a; 22b; 221b, 222b); a first supply line that is adapted to supply injection oil to the rotor chamber (38; 38d, 38e); a second supply line that is provided independent of the first supply line and adapted to supply lubrication oil to the bearing; and a third supply line that is adapted to supply sealing gas to the first shaft-sealing part (32; 32a, 32b), characterized by a second shaft-sealing part (34; 34c, 34d) that is provided on a discharge side of the compressor to line up with the first shaft-sealing part (32; 32a, 32b) between the rotor chamber (38; 38d, 38e) and the bearing in the casing to seal the periphery of the rotor shaft (22a; 22b; 221b, 222b); and a fourth supply line (12; 12a, 12b) that is adapted to supply the second shaft-sealing part (34; 34c, 34d) with sealing oil to be used for sealing at the second shaft-sealing part (34; 34c, 34d). a compressor including a casing having a rotor chamber (38; 38d, 38e), a rotor that is housed in the rotor chamber (38; 38d, 38e) inside the casing and configured to compress gas by rotating, a rotor shaft (22a; 22b; 221b, 222b) that extends from the rotor, a bearing that is provided inside the casing and supports the rotor shaft (22a; 22b; 221b, 222b) so that the rotor is rotatable, and a first shaft-sealing part (32; 32a, 32b) that is provided between the rotor chamber (38; 38d, 38e) and the bearing in the casing to seal a periphery of the rotor shaft (22a; 22b; 221b, 222b); a casing having a rotor chamber (38; 38d, 38e), a rotor that is housed in the rotor chamber (38; 38d, 38e) inside the casing and configured to compress gas by rotating, a rotor shaft (22a; 22b; 221b, 222b) that extends from the rotor, a bearing that is provided inside the casing and supports the rotor shaft (22a; 22b; 221b, 222b) so that the rotor is rotatable, and a first shaft-sealing part (32; 32a, 32b) that is provided between the rotor chamber (38; 38d, 38e) and the bearing in the casing to seal a periphery of the rotor shaft (22a; 22b; 221b, 222b); a first supply line that is adapted to supply injection oil to the rotor chamber (38; 38d, 38e); a second supply line that is provided independent of the first supply line and adapted to supply lubrication oil to the bearing; and a third supply line that is adapted to supply sealing gas to the first shaft-sealing part (32; 32a, 32b), characterized by a second shaft-sealing part (34; 34c, 34d) that is provided on a discharge side of the compressor to line up with the first shaft-sealing part (32; 32a, 32b) between the rotor chamber (38; 38d, 38e) and the bearing in the casing to seal the periphery of the rotor shaft (22a; 22b; 221b, 222b); and a fourth supply line (12; 12a, 12b) that is adapted to supply the second shaft-sealing part (34; 34c, 34d) with sealing oil to be used for sealing at the second shaft-sealing part (34; 34c, 34d).