To provide a rotary shaft vibration characteristic tester, excelling in workability, versatility, and reliability, for simultaneously generating out-of-plane bending vibration and torsional vibration on a rotary shaft by a simple structure, reproducing the mode of vibration generated on a rotary shaft in an actual mechanical system, used for easily performing measurement on rotation speed of a rotary shaft or analysis, etc. on a vibration state under various conditions, precisely testing the vibration characteristics of a rotary shaft in consideration of an effect of centrifugal force, and used for easily and accurately setting an arbitrary amplitude of rotation speed which is a torsional vibration input.

This tester is equipped with a base, one or more bearing parts disposed on the base, an output rotary shaft inserted through and supported by the bearing parts, a universal joint with one end thereof connected to an end part of the output rotary shaft, an input rotary shaft connected to the other end of the universal joint, a motor linked to the input rotary shaft for rotating the input rotary shaft, and a motor angle variably-fixing part disposed or formed on the base for fixing the motor in a fixed-angle variable manner by arbitrarily setting a crossing angle which the output rotary shaft forms with the input rotary shaft so as to center on the universal joint.