To provide a torque transmission device capable of reducing the occurrence of an asynchronous magnetic flux wave component, and provide a gas turbine generator using the torque transmission device.

A rotation torque transmission device includes: an outside rotor; an outside rotor magnet; an inside rotor; an inside rotor magnet; a magnetic path member 2; and an inclined magnetic path member 6. The inclined magnetic path member 6 is configured such that a surface opposite to the outside rotor magnet moves in a circumferential direction by odd times of the half wavelength of an asynchronous magnetic flux wave to be a magnetic flux wave not synchronous with rotation of the outside rotor, in the magnetic path member 2.