A velocity measurement device for measuring a velocity of a vehicle running on a road, the velocity measurement device comprising: a transmitting means that is configured to transmit a transmission signal (f T) by a transmitting antenna toward a measurement object; a receiving means that is configured to receive a reflected wave (Rw) from the measurement object with a plurality of receiving antennas and to generate a reception signal (f R) for each of the receiving antennas; and a signal processing means that is configured to obtain a phase plane of the reflected wave with respect to an antenna plane of the plurality of receiving antennas from a phase difference between the reception signals to specify an arrival direction of the reflected wave, to obtain a distance to the measurement object from a propagation delay time of the reflected wave, and to calculate a phase fluctuation of the reflected wave to calculate a velocity of the measurement object from the phase fluctuation, wherein: the velocity measurement device is fixedly disposed above the road, on a shoulder of the road or on a median strip of the road, or is to be fixedly disposed above the road, on the shoulder of the road or on the median strip of the road, the signal processing means is configured to transform, with fast Fourier transform in the time direction, plotted phase information of the measurement object shown in a plurality of image planes that each have two axes representing the distance to and an azimuth of the measurement object respectively and are formed on a time axis of measurement data obtained during a data acquisition period (Tp) to calculate the velocity of the measurement object, and the data acquisition period is represented by the following inequality Tp ≥ λ / 0.556 wherein Tp is the data acquisition period in seconds, and λ is a wavelength of the transmission signal in meters. a transmitting means that is configured to transmit a transmission signal (f T) by a transmitting antenna toward a measurement object; a receiving means that is configured to receive a reflected wave (Rw) from the measurement object with a plurality of receiving antennas and to generate a reception signal (f R) for each of the receiving antennas; and a signal processing means that is configured to obtain a phase plane of the reflected wave with respect to an antenna plane of the plurality of receiving antennas from a phase difference between the reception signals to specify an arrival direction of the reflected wave, to obtain a distance to the measurement object from a propagation delay time of the reflected wave, and to calculate a phase fluctuation of the reflected wave to calculate a velocity of the measurement object from the phase fluctuation, wherein: the velocity measurement device is fixedly disposed above the road, on a shoulder of the road or on a median strip of the road, or is to be fixedly disposed above the road, on the shoulder of the road or on the median strip of the road, the signal processing means is configured to transform, with fast Fourier transform in the time direction, plotted phase information of the measurement object shown in a plurality of image planes that each have two axes representing the distance to and an azimuth of the measurement object respectively and are formed on a time axis of measurement data obtained during a data acquisition period (Tp) to calculate the velocity of the measurement object, and the data acquisition period is represented by the following inequality Tp ≥ λ / 0.556 wherein Tp is the data acquisition period in seconds, and λ is a wavelength of the transmission signal in meters.