A seal structure (3c) for a steam turbine (2) is provided, which is capable of suppressing transfer of heat generated by a friction between a rotating portion and a fixed portion to the rotating portion and of suppressing an increase in the temperature of the rotating portion. A labyrinth seal device (3c) serves to suppress the amount of steam (St) leaking from a clearance present between each stator blade (2c) (fixed portion) of the steam turbine (2) and a rotor (2a) (rotating portion). The seal structure (3c) for the steam turbine (2) is formed to ensure that permeable spacers (4) made of a permeable metal are provided on the rotor (2a) and a seal stationary body (3c1) and face respective seal fins (3b1) provided in the labyrinth seal device (3c).