A fluid machine (1a-1f) comprising: a multi-stage compressor that includes a first compressor having a first inlet and a first outlet, a second compressor having a second inlet and a second outlet, and a bearing supporting a shaft for driving at least one of the first compressor and the second compressor, the first compressor sucking a gas refrigerant through the first inlet, compressing the gas refrigerant, and discharging the gas refrigerant through the first outlet, the second compressor sucking the gas refrigerant discharged from the first outlet through the second inlet, compressing the gas refrigerant, and discharging the gas refrigerant through the second outlet; a pressure container that stores a liquid lubricant whose main component is the same kind of substance as a main component of the refrigerant; a first supply path through which the liquid lubricant stored in the pressure container is supplied to the bearing, the first supply path connecting the pressure container with the bearing; a pump that is disposed on the first supply path and pumps the liquid lubricant toward the bearing; a first return path through which the liquid lubricant that has passed through the bearing is returned to the pressure container, the first return path connecting the bearing with the pressure container; and an intermediate pressure space that is maintained at a pressure higher than a pressure of the gas refrigerant at the first inlet and lower than a pressure of the gas refrigerant at the second outlet during operation of the multi-stage compressor, wherein an internal space of the pressure container constitutes a part of the intermediate pressure space. a multi-stage compressor that includes a first compressor having a first inlet and a first outlet, a second compressor having a second inlet and a second outlet, and a bearing supporting a shaft for driving at least one of the first compressor and the second compressor, the first compressor sucking a gas refrigerant through the first inlet, compressing the gas refrigerant, and discharging the gas refrigerant through the first outlet, the second compressor sucking the gas refrigerant discharged from the first outlet through the second inlet, compressing the gas refrigerant, and discharging the gas refrigerant through the second outlet; a pressure container that stores a liquid lubricant whose main component is the same kind of substance as a main component of the refrigerant; a first supply path through which the liquid lubricant stored in the pressure container is supplied to the bearing, the first supply path connecting the pressure container with the bearing; a pump that is disposed on the first supply path and pumps the liquid lubricant toward the bearing; a first return path through which the liquid lubricant that has passed through the bearing is returned to the pressure container, the first return path connecting the bearing with the pressure container; and an intermediate pressure space that is maintained at a pressure higher than a pressure of the gas refrigerant at the first inlet and lower than a pressure of the gas refrigerant at the second outlet during operation of the multi-stage compressor, wherein an internal space of the pressure container constitutes a part of the intermediate pressure space.