An expander-integrated compressor (100) includes: a compression mechanism (2) for compressing a working fluid; an expansion mechanism (3) for expanding a working fluid; and a shaft (5) that couples the compression mechanism (2) and the expansion mechanism (3). The expansion mechanism (3) includes a variable vane mechanism (60). The variable vane mechanism (60) controls the movement of a first vane (48) so that the ratio of a period P2 to a period P1 (P2/P1) can be adjusted, where P1 denotes the period during which the first vane (48) is in contact with a first piston (46) in the course of one rotation of the shaft (5), and P2 denotes the period during which the first vane (48) is spaced from the first piston (46) in the course of one rotation of the shaft (5).