A superconducting rotating machine comprising: a rotating shaft having a first annular sliding surface on one side in an axial direction; a torque tube fixed to the other side in the axial direction of the rotating shaft; a rotating shaft supporting part having a second annular sliding surface slidable in the axial direction on the first sliding surface and radially supporting the rotating shaft in a state of being relatively movable in the axial direction with respect to the rotating shaft; and a superconducting coil held by the rotating shaft and cooled by a coolant supplied from one end side or the other end side in the axial direction of the rotating shaft, characterised by: at least one of the first sliding surface of the rotating shaft and the second sliding surface of the rotating shaft supporting part having a surface of a hard coating film (51, 56) located to partially cover a heat input suppressing part (50, 55) made of a fiber-reinforced plastic, the hard coating film (51, 56) being harder than the heat input suppressing part (50, 55), and wherein an axial end surface of the hard coating film (51, 56) is connected to a surface of the heat input suppressing part (50, 55) in a smooth and continuous manner, said two surfaces (41, 42) forming a continuous curve, a boundary of the hard coating film (51, 56) and the heat input suppressing part (50, 55) is parallel to the axis of the machine, and the angle between the boundary and the continuous curve, in the side of the hard coating film and the heat input suppressing part is an acute angle on a hard coating film (51, 56) side and an obtuse angle on a heat input suppressing part (50, 55) side. a rotating shaft having a first annular sliding surface on one side in an axial direction; a torque tube fixed to the other side in the axial direction of the rotating shaft; a rotating shaft supporting part having a second annular sliding surface slidable in the axial direction on the first sliding surface and radially supporting the rotating shaft in a state of being relatively movable in the axial direction with respect to the rotating shaft; and a superconducting coil held by the rotating shaft and cooled by a coolant supplied from one end side or the other end side in the axial direction of the rotating shaft, characterised by: at least one of the first sliding surface of the rotating shaft and the second sliding surface of the rotating shaft supporting part having a surface of a hard coating film (51, 56) located to partially cover a heat input suppressing part (50, 55) made of a fiber-reinforced plastic, the hard coating film (51, 56) being harder than the heat input suppressing part (50, 55), and wherein an axial end surface of the hard coating film (51, 56) is connected to a surface of the heat input suppressing part (50, 55) in a smooth and continuous manner, said two surfaces (41, 42) forming a continuous curve, a boundary of the hard coating film (51, 56) and the heat input suppressing part (50, 55) is parallel to the axis of the machine, and the angle between the boundary and the continuous curve, in the side of the hard coating film and the heat input suppressing part is an acute angle on a hard coating film (51, 56) side and an obtuse angle on a heat input suppressing part (50, 55) side. at least one of the first sliding surface of the rotating shaft and the second sliding surface of the rotating shaft supporting part having a surface of a hard coating film (51, 56) located to partially cover a heat input suppressing part (50, 55) made of a fiber-reinforced plastic, the hard coating film (51, 56) being harder than the heat input suppressing part (50, 55), and wherein an axial end surface of the hard coating film (51, 56) is connected to a surface of the heat input suppressing part (50, 55) in a smooth and continuous manner, said two surfaces (41, 42) forming a continuous curve, a boundary of the hard coating film (51, 56) and the heat input suppressing part (50, 55) is parallel to the axis of the machine, and the angle between the boundary and the continuous curve, in the side of the hard coating film and the heat input suppressing part is an acute angle on a hard coating film (51, 56) side and an obtuse angle on a heat input suppressing part (50, 55) side.