A steam turbine includes: a partition section that partitions a high-pressure stage and a low-pressure stage; and a pressure regulation valve that regulates a pressure of extraction steam. The pressure regulation valve includes: a plurality of flow rate regulation valves; and a plurality of flow path compartments that correspond to the respective flow rate regulation valves and that communicate with the low-pressure stage side relative to the partition section through respective nozzle holes. The plurality of flow path compartments are arranged over the entire partition section in a circumferential direction in a region including an outer peripheral side of the pressure regulation valve relative to the partition section as a whole. The partition section includes a bypass passage that makes the high-pressure stage side and the low-pressure stage side communicate with each other without passing through the pressure regulation valve.