A steam turbine disposed on a foundation, the steam turbine comprising: an outer casing; an inner casing housed in the outer casing and having an inner casing upper half portion and an inner casing lower half portion; a nozzle diaphragm constituted by a nozzle diaphragm lower half portion and a nozzle diaphragm upper half portion; a turbine rotor penetrating the inner casing and the outer casing; and a support beam provided in the outer casing, extending in an axial direction of the turbine rotor, and supporting the inner casing, wherein the outer casing comprises: outer casing support portions provided in both end portions of the outer casing in the axial direction of the turbine rotor and supported by the foundation, the support beam comprises: beam end portions provided in both end portions in the axial direction of the turbine rotor, the outer casing support portion comprises: a support surface supporting the beam end portion, wherein the steam turbine further comprises: a low-friction member intervening between the beam end portion and the support surface, a surface of the low-friction member having of a lower friction coefficient than the friction coefficient of the support surface, and the outer casing includes a height adjustment mechanism characterized in that the height adjustment mechanism is capable of accessing the beam end portion from the outside of the outer casing and includes: a height adjustment screw provided above the beam end portion, so that, when deflection occurs in the support beam in a Tops On state in which the nozzle diaphragm upper half portion is disposed on the nozzle diaphragm lower half portion and the inner casing upper half portion is disposed on the inner casing lower half portion, and the support beam is in a state where, with a fulcrum being an inner point on a lower surface of the beam end portion in contact with an upper surface of the low-friction member, an outer point on a tip side of the beam end portion floats upwards, the beam end portion is pushed downward in the vertical direction (z) by turning the height adjustment screw in the outside of the outer casing, and thereby a center portion of the support beam moves upward with the inner point being a fulcrum. an outer casing; an inner casing housed in the outer casing and having an inner casing upper half portion and an inner casing lower half portion; a nozzle diaphragm constituted by a nozzle diaphragm lower half portion and a nozzle diaphragm upper half portion; a turbine rotor penetrating the inner casing and the outer casing; and a support beam provided in the outer casing, extending in an axial direction of the turbine rotor, and supporting the inner casing, wherein the outer casing comprises: outer casing support portions provided in both end portions of the outer casing in the axial direction of the turbine rotor and supported by the foundation, the support beam comprises: beam end portions provided in both end portions in the axial direction of the turbine rotor, the outer casing support portion comprises: a support surface supporting the beam end portion, a low-friction member intervening between the beam end portion and the support surface, a surface of the low-friction member having of a lower friction coefficient than the friction coefficient of the support surface, and the outer casing includes a height adjustment mechanism characterized in that the height adjustment mechanism is capable of accessing the beam end portion from the outside of the outer casing and includes: a height adjustment screw provided above the beam end portion, so that, when deflection occurs in the support beam in a Tops On state in which the nozzle diaphragm upper half portion is disposed on the nozzle diaphragm lower half portion and the inner casing upper half portion is disposed on the inner casing lower half portion, and the support beam is in a state where, with a fulcrum being an inner point on a lower surface of the beam end portion in contact with an upper surface of the low-friction member, an outer point on a tip side of the beam end portion floats upwards, the beam end portion is pushed downward in the vertical direction (z) by turning the height adjustment screw in the outside of the outer casing, and thereby a center portion of the support beam moves upward with the inner point being a fulcrum.