To prevent abrasion of and damage to the turbine rotor shaft of a stopped exhaust turbine supercharger and a radial bearing bearingly supporting the turbine rotor shaft.

This supercharger turning device 20 turns the exhaust turbine supercharger 1 driven by exhaust gas introduced from an internal combustion engine and supplying compressed air to the internal combustion engine. The supercharger turning device includes a geared motor 22 which is configured to be attached/detached to/from the exhaust turbine supercharger 1, and to rotate the turbine rotor shaft 2 at such a rotational speed ensuring the minimum thickness of an oil film formed between the turbine rotor shaft 2 and the radial bearing 16 that the abrasion speed of the bearing caused by foreign matter supposed to be contained in lubricating oil supplied to the radial bearing 16 bearingly supporting the turbine rotor shaft 2 composing the exhaust turbine supercharger 1, in the supercharger during stop, becomes equivalent to or slower than the abrasion speed of the bearing during the normal operation of the supercharger.