A two-stage rotary expander comprising: a first cylinder; a first closing member for closing one end of the first cylinder; an intermediate closing member for closing the other end of the first cylinder; a second cylinder having one end closed by the intermediate closing member; a second closing member for closing the other end of the second cylinder; a first piston disposed in the first cylinder to form a first working chamber in the first cylinder together with the first closing member and the intermediate closing member, the first piston being configured to perform an eccentric rotational motion in the first cylinder; a second piston disposed in the second cylinder to form a second working chamber in the second cylinder together with the intermediate closing member and the second closing member, the second piston being configured to perform an eccentric rotational motion in the second cylinder; a first partition member for partitioning the first working chamber into an upstream first working chamber and a downstream first working chamber; a second partition member for partitioning the second working chamber into an upstream second working chamber and a downstream second working chamber; a suction port facing the upstream first working chamber; a communication passage formed in the intermediate closing member and having one end facing the downstream first working chamber and the other end facing the upstream second working chamber; and a discharge port facing the downstream second working chamber, characterised in that the one end of the communication passage is provided at a position located inwardly away from an inner circumferential surface of the first cylinder so that the one end of the communication passage is kept from being connected to the suction port. a first cylinder; a first closing member for closing one end of the first cylinder; an intermediate closing member for closing the other end of the first cylinder; a second cylinder having one end closed by the intermediate closing member; a second closing member for closing the other end of the second cylinder; a first piston disposed in the first cylinder to form a first working chamber in the first cylinder together with the first closing member and the intermediate closing member, the first piston being configured to perform an eccentric rotational motion in the first cylinder; a second piston disposed in the second cylinder to form a second working chamber in the second cylinder together with the intermediate closing member and the second closing member, the second piston being configured to perform an eccentric rotational motion in the second cylinder; a first partition member for partitioning the first working chamber into an upstream first working chamber and a downstream first working chamber; a second partition member for partitioning the second working chamber into an upstream second working chamber and a downstream second working chamber; a suction port facing the upstream first working chamber; a communication passage formed in the intermediate closing member and having one end facing the downstream first working chamber and the other end facing the upstream second working chamber; and a discharge port facing the downstream second working chamber, characterised in that the one end of the communication passage is provided at a position located inwardly away from an inner circumferential surface of the first cylinder so that the one end of the communication passage is kept from being connected to the suction port.