A turbine system including a turbine comprising: a casing (18, 19); a rotor shaft penetrating the casing (18, 19); a plurality of turbine stages arranged in the casing (18, 19) along an axial direction of the rotor shaft; a thrust bearing which receives thrust load in the axial direction generated by a flow of a working fluid supplied to the turbine stages; and a balance piston which is formed on the rotor shaft along a circumferential direction and projects in a radial direction from the rotor shaft, for adjusting a thrust contact pressure applied to the thrust bearing; a compressor configured to pressurize working fluid discharged from the turbine; and a thrust load adjusting mechanism which applies pressures of a pressure-increasing side and a pressure-decreasing side to at least one of a balance piston inner-side chamber and a balance piston outer-side chamber which sandwich the balance piston in the axial direction; characterized in that the thrust load adjusting mechanism comprises: a low pressure-side pipe connected to a low-pressure region defined between an exhaust side of the turbine and a suction side of a compressor; a high pressure-side pipe connected to a high-pressure region defined between a discharge side of the compressor and an inlet side of the turbine; a low pressure-side control valve (121, 123) disposed on the low pressure-side pipe; a high pressure-side control valve (122, 124) disposed on the high pressure-side pipe; and a controller which outputs an opening or closing command to the low pressure-side control valve (121, 123) and the high pressure-side control valve (122, 124), wherein the low pressure-side pipe and the high pressure-side pipe communicate with at least one of the balance piston inner-side chamber and the balance piston outer-side chamber. a turbine comprising: a casing (18, 19); a rotor shaft penetrating the casing (18, 19); a plurality of turbine stages arranged in the casing (18, 19) along an axial direction of the rotor shaft; a thrust bearing which receives thrust load in the axial direction generated by a flow of a working fluid supplied to the turbine stages; and a balance piston which is formed on the rotor shaft along a circumferential direction and projects in a radial direction from the rotor shaft, for adjusting a thrust contact pressure applied to the thrust bearing; a casing (18, 19); a rotor shaft penetrating the casing (18, 19); a plurality of turbine stages arranged in the casing (18, 19) along an axial direction of the rotor shaft; a thrust bearing which receives thrust load in the axial direction generated by a flow of a working fluid supplied to the turbine stages; and a balance piston which is formed on the rotor shaft along a circumferential direction and projects in a radial direction from the rotor shaft, for adjusting a thrust contact pressure applied to the thrust bearing; a compressor configured to pressurize working fluid discharged from the turbine; and a thrust load adjusting mechanism which applies pressures of a pressure-increasing side and a pressure-decreasing side to at least one of a balance piston inner-side chamber and a balance piston outer-side chamber which sandwich the balance piston in the axial direction; characterized in that the thrust load adjusting mechanism comprises: a low pressure-side pipe connected to a low-pressure region defined between an exhaust side of the turbine and a suction side of a compressor; a high pressure-side pipe connected to a high-pressure region defined between a discharge side of the compressor and an inlet side of the turbine; a low pressure-side control valve (121, 123) disposed on the low pressure-side pipe; a high pressure-side control valve (122, 124) disposed on the high pressure-side pipe; and a controller which outputs an opening or closing command to the low pressure-side control valve (121, 123) and the high pressure-side control valve (122, 124), wherein the low pressure-side pipe and the high pressure-side pipe communicate with at least one of the balance piston inner-side chamber and the balance piston outer-side chamber. a low pressure-side pipe connected to a low-pressure region defined between an exhaust side of the turbine and a suction side of a compressor; a high pressure-side pipe connected to a high-pressure region defined between a discharge side of the compressor and an inlet side of the turbine; a low pressure-side control valve (121, 123) disposed on the low pressure-side pipe; a high pressure-side control valve (122, 124) disposed on the high pressure-side pipe; and a controller which outputs an opening or closing command to the low pressure-side control valve (121, 123) and the high pressure-side control valve (122, 124), wherein the low pressure-side pipe and the high pressure-side pipe communicate with at least one of the balance piston inner-side chamber and the balance piston outer-side chamber.