An experimental apparatus of journal bearings for rotor vibration was used in this study. A rotor, composed of a shaft, a weight, one piece of a clutch and a slight disk having many slits for pulse generation, was supported by a pair of journal bearings. The rotor was rotated by an electric motor and then separated from it. The vibrations of the rotor, at the journal and at the weight, were measured with gap sensors and laser displacement sensors. Vibration of rotor supported by journal bearings was analyzed with FFT analyzer. Frequencies of critical speed and oil whip are shown in comparison with each other.