PURPOSE: To provide a high speed spin testing device by which a balance is easily adjusted and vibration is not caused even when passing through at primary or high order dangeous speed.

CONSTITUTION: A high speed spin testing device is provided with a driving device 10 which is arranged on an upper cover 91 and to which a rotary shaft 11 extending in a housing 90 is joined, a connecting shaft 15 coaxially joined to the rotary shaft 11, a horizontal disk-shaped test object 50 in which a concentrically circular installing hole 51 is bored and concentric annular grooves 52 are formed on the outside and an under surface, a test object installing mandrel 60 coaxially installed on the connecting shaft 15, a test object installing jig 70 which is fitted to faucet parts of upper and lower two places on the outside of the mandrel 60 and in which a flange 71 is integrally joined to an intermediate part and an annular protrusion 72 is protrusively arranged on the periphery so as to be fitted in the annular grooves 52 of the test object 50 and on which the test object 50 is installed and emergency bearings 85 and 86 which have a damping function and are arranged around upper and lower two places of a bearing device 80 and the test object installing jig 70.