The invention refers to a bearing structure (24) for bearing a shaft portion (14) of a rotor tail end (10) of a gas turbine, comprising: a rotor assembly of the gas turbine having a center axis (0); rotor blades of the gas turbine; a steam passage (20) extending along the center axis for supplying and recovering a steam for cooling the rotor blades; a bearing pad (24a) which forms a journal bearing; and seal portions (26c) provided on opposite sides of the bearing pad in the axial direction to prevent leakage of a lubricant for lubricating a space between the bearing pad and the shaft portion, the width of said seal portion in the axial direction being such that the surface temperature of the shaft portion of the rotor tail end is maintained below a predetermined temperature by the lubricant, within the width of the bearing pad in the axial direction.