A toroidal continuously variable transmission comprising: a first transmission unit including: a first input disc and a first output disc disposed coaxially with each other; and a first power roller tiltably interposed between the first input disc and the first output disc and configured to transmit a driving force from the first input disc to the first output disc; and a second transmission unit disposed coaxially with the first transmission unit, the second transmission unit including: a second input disc and a second output disc disposed coaxially with each other; and a second power roller tiltably interposed between the second input disc and the second output disc and configured to transmit a driving force from the second input disc to the second output disc, the second transmission unit being disposed such that a back surface of the second input disc is opposed to a back surface of the first input disc, wherein the back surface of the first input disc is provided with a back surface cylinder wall of a tubular shape protruding therefrom so as to be concentric with the first input disc, and the back surface of the second input disc is provided with a back surface cylinder wall of a tubular shape protruding therefrom so as to be concentric with the second input disc, wherein each back surface cylinder wall (51, 53) has an outer periphery connected to an input gear configured to input power to the toroidal continuously variable transmission, the outer periphery being connected to the input gear so as to be non-rotatable relative to each other characterized in that a first bearing is provided between an inner peripheral surface of the back surface cylinder wall of the first input disk and an outer peripheral surface of an input shaft, the first bearing rotatably supporting the first input disc and the input gear on the input shaft, and a second bearing is provided between an inner peripheral surface of the back surface cylinder wall of the second input disc and the outer peripheral surface of the input shaft, the second bearing rotatably supporting the second input disk and the input gear on the input shaft. a first transmission unit including: a first input disc and a first output disc disposed coaxially with each other; and a first power roller tiltably interposed between the first input disc and the first output disc and configured to transmit a driving force from the first input disc to the first output disc; and a first input disc and a first output disc disposed coaxially with each other; and a first power roller tiltably interposed between the first input disc and the first output disc and configured to transmit a driving force from the first input disc to the first output disc; and a second transmission unit disposed coaxially with the first transmission unit, the second transmission unit including: a second input disc and a second output disc disposed coaxially with each other; and a second power roller tiltably interposed between the second input disc and the second output disc and configured to transmit a driving force from the second input disc to the second output disc, the second transmission unit being disposed such that a back surface of the second input disc is opposed to a back surface of the first input disc, a second input disc and a second output disc disposed coaxially with each other; and a second power roller tiltably interposed between the second input disc and the second output disc and configured to transmit a driving force from the second input disc to the second output disc, the second transmission unit being disposed such that a back surface of the second input disc is opposed to a back surface of the first input disc, wherein the back surface of the first input disc is provided with a back surface cylinder wall of a tubular shape protruding therefrom so as to be concentric with the first input disc, and the back surface of the second input disc is provided with a back surface cylinder wall of a tubular shape protruding therefrom so as to be concentric with the second input disc, wherein each back surface cylinder wall (51, 53) has an outer periphery connected to an input gear configured to input power to the toroidal continuously variable transmission, the outer periphery being connected to the input gear so as to be non-rotatable relative to each other characterized in that a first bearing is provided between an inner peripheral surface of the back surface cylinder wall of the first input disk and an outer peripheral surface of an input shaft, the first bearing rotatably supporting the first input disc and the input gear on the input shaft, and a second bearing is provided between an inner peripheral surface of the back surface cylinder wall of the second input disc and the outer peripheral surface of the input shaft, the second bearing rotatably supporting the second input disk and the input gear on the input shaft.