An intermediate intake-type diaphragm includes a flow-regulating vane that is provided in an introduction flow channel to regulate a first fluid to flow along the radial direction; and a partition wall that partitions the introduction flow channel and an intermediate suction flow channel in the direction of an axial line. A radially inner end portion of the partition wall is located further on a radially inner side than a radially outer end portion of the flow-regulating vane, and further on a radially outer side than a boundary between the introduction flow channel and a curved flow channel.