A turbine blade mounting structure in which a turbine blade is mounted to an outer circumferential edge of a disc to be rotationally driven, the turbine blade mounting structure comprising: a fitting section formed by fitting an end portion on an inner circumferential side of the turbine blade to a groove extending in a direction of a rotation axis at the outer circumferential edge of the disc; a shielding member which is disposed on an end surface on an upstream side of the fitting section to shield fluid flowing to the fitting section; and a support section which supports an end portion on an outer circumferential side of the shielding member at least when the disc is rotationally driven, wherein a guiding surface expanding to the outer circumferential side from the upstream side toward the downstream side is formed on the support section, a guided surface expanding to the outer circumferential side from the upstream side toward the downstream side is formed at an end portion on the outer circumferential side of the shielding member, and the shielding member covers a gap between the disc and the turbine blade in the fitting section in a state in which the guided surface abuts against the guiding surface at least when the disc is rotationally driven, characterized in that: when the disc is rotationally driven, a centrifugal force acts on the shielding member such that the guided surface of the shielding member is brought into contact with and pressed against the guiding surface of the support section causing the guided surface to move along the guiding surface and the whole shielding member to move toward the downstream side until an end surface on the downstream side of the shielding member comes into contact with and is pressed against the end surface on the upstream side of the fitting section in a state of covering the gap. a fitting section formed by fitting an end portion on an inner circumferential side of the turbine blade to a groove extending in a direction of a rotation axis at the outer circumferential edge of the disc; a shielding member which is disposed on an end surface on an upstream side of the fitting section to shield fluid flowing to the fitting section; and a support section which supports an end portion on an outer circumferential side of the shielding member at least when the disc is rotationally driven, wherein a guiding surface expanding to the outer circumferential side from the upstream side toward the downstream side is formed on the support section, a guided surface expanding to the outer circumferential side from the upstream side toward the downstream side is formed at an end portion on the outer circumferential side of the shielding member, and the shielding member covers a gap between the disc and the turbine blade in the fitting section in a state in which the guided surface abuts against the guiding surface at least when the disc is rotationally driven, characterized in that: when the disc is rotationally driven, a centrifugal force acts on the shielding member such that the guided surface of the shielding member is brought into contact with and pressed against the guiding surface of the support section causing the guided surface to move along the guiding surface and the whole shielding member to move toward the downstream side until an end surface on the downstream side of the shielding member comes into contact with and is pressed against the end surface on the upstream side of the fitting section in a state of covering the gap.