An interferometric vibration observation device includes a transmitting unit, a receiving unit and a signal processing unit. The transmitting unit transmits a transmission signal toward an observation object. The receiving unit receives a reflection wave from the observation object with a plurality of receiving antennas and generates a reception signal for each of the receiving antennas. The signal processing unit obtains a phase plane of the reflection wave to an antenna plane from a phase difference between the reception signals, identifies an arrival direction and a signal strength of the reflection wave, calculates a phase variation of the reflection wave from a certain direction, and generates an observation signal representative of a vibration of the observation object or a certain site of the observation object.