An expander-compressor unit (200) includes a closed casing (1), a compression mechanism (2) disposed at an upper position in the closed casing (1), an expansion mechanism (3) disposed at a lower position in the closed casing (1), a shaft (5) coupling the compression mechanism (2) to the expansion mechanism (3), and an oil pump (6) disposed between the compression mechanism (2) and the expansion mechanism (3). The oil pump (6) supplies the oil held in an oil reservoir (25) to the compression mechanism (2) via a suction passage. A strainer (65) is provided to the suction passage so that the oil to be drawn into the oil pump (6) passes through the strainer.