A vibration-type rheometer comprises a vibration-type viscometer having a pair of vibrator subassemblies which resonate as in a tuning fork. The pair of vibrator subassemblies constituting a tuning fork vibrator each has at its free end a sensor plate formed from a thin metal plate places into a sample to be measured, and the vibrator subassemblies are driven at the same frequency but in opposite phase relationship to each other by an electromagnetic driving unit together with the sensor plates. A control unit supplies a time-varying driving current whose magnitude varies with time to the electromagnetic driving unit in order to change the vibration-applying force applied to the pair of vibrator subassemblies. The amplitude of vibration of the vibrator subassemblies changes as a function of the viscous resistance encountered by the sensor plates from the sample and the amplitude is electrically detected, and the detected value is sent to a recording unit together with the value of the driving current to thereby indicate the behavior of the sample.