A coupling device configured to transmit a rotational force between a first shaft and a second shaft, the device comprising: a first coupling member configured to relatively non-rotatably be mounted on the first shaft; a second coupling member configured to relatively non-rotatably be mounted on the second shaft; and an intermediate member disposed between the first coupling member and the second coupling member in an extension direction of an axis of the coupling device, the intermediate member being fixed to each of the first coupling member and the second coupling member, and being configured to allow misalignment between the first shaft and the second shaft, wherein the second coupling member includes: a base member configured to be fixed to the intermediate member by a first fastening device; and a shaft mounting member configured to relatively non-rotatably be mounted on the second shaft, the shaft mounting member having a long hole extending along a circumferential direction of the axis and being configured to detachably be fixed to the base member by a second fastening device inserted through the long hole, characterised in that one member of the base member and the shaft mounting member includes a protruding shaft portion which protrudes from an end surface facing another end surface to be coaxial with the axis in the extension direction of the axis and is formed to have a circular cross-section orthogonal to the axis wherein the other member of the base member and the shaft mounting member includes a fitting hole portion which is disposed in the another end surface and is configured to be fitted with the protruding shaft portion, the other member having an inner circumferential surface formed to have a circular cross-section orthogonal to the axis; and wherein the protruding shaft portion is inserted into the fitting hole portion and is configured to slidingly be rotatable in a state where an outer circumferential surface of the protruding shaft portion 81) is in contact with the inner circumferential surface of the fitting hole portion. a first coupling member configured to relatively non-rotatably be mounted on the first shaft; a second coupling member configured to relatively non-rotatably be mounted on the second shaft; and an intermediate member disposed between the first coupling member and the second coupling member in an extension direction of an axis of the coupling device, the intermediate member being fixed to each of the first coupling member and the second coupling member, and being configured to allow misalignment between the first shaft and the second shaft, wherein the second coupling member includes: a base member configured to be fixed to the intermediate member by a first fastening device; and a shaft mounting member configured to relatively non-rotatably be mounted on the second shaft, the shaft mounting member having a long hole extending along a circumferential direction of the axis and being configured to detachably be fixed to the base member by a second fastening device inserted through the long hole, characterised in that one member of the base member and the shaft mounting member includes a protruding shaft portion which protrudes from an end surface facing another end surface to be coaxial with the axis in the extension direction of the axis and is formed to have a circular cross-section orthogonal to the axis wherein the other member of the base member and the shaft mounting member includes a fitting hole portion which is disposed in the another end surface and is configured to be fitted with the protruding shaft portion, the other member having an inner circumferential surface formed to have a circular cross-section orthogonal to the axis; and wherein the protruding shaft portion is inserted into the fitting hole portion and is configured to slidingly be rotatable in a state where an outer circumferential surface of the protruding shaft portion 81) is in contact with the inner circumferential surface of the fitting hole portion. a base member configured to be fixed to the intermediate member by a first fastening device; and a shaft mounting member configured to relatively non-rotatably be mounted on the second shaft, the shaft mounting member having a long hole extending along a circumferential direction of the axis and being configured to detachably be fixed to the base member by a second fastening device inserted through the long hole, characterised in that one member of the base member and the shaft mounting member includes a protruding shaft portion which protrudes from an end surface facing another end surface to be coaxial with the axis in the extension direction of the axis and is formed to have a circular cross-section orthogonal to the axis wherein the other member of the base member and the shaft mounting member includes a fitting hole portion which is disposed in the another end surface and is configured to be fitted with the protruding shaft portion, the other member having an inner circumferential surface formed to have a circular cross-section orthogonal to the axis; and wherein the protruding shaft portion is inserted into the fitting hole portion and is configured to slidingly be rotatable in a state where an outer circumferential surface of the protruding shaft portion 81) is in contact with the inner circumferential surface of the fitting hole portion.