An expander-compressor unit (30) includes: a closed casing (1) holding an oil at a bottom portion thereof; a motor (2) provided in the closed casing (1); a compression mechanism (3) for compressing a refrigerant and discharging it into the closed casing (1), the compression mechanism (3) being disposed below the motor (2) in the closed casing (1); an expansion mechanism (4) disposed below the compression mechanism (3) in the closed casing (1); and a coupling mechanism (50) for coupling a compression mechanism side shaft (5) to an expansion mechanism side shaft (6). An oil supply passage (53) for supplying the oil to the compression mechanism (3) is formed in the compression mechanism side shaft (5). An oil suction port (53A) is provided in a portion of the compression mechanism side shaft (5), the portion being above the expansion mechanism (4).