A signal processing device, comprising: an echo signal input unit adapted to receive echo signals resulted from transmission signals reflected on an object, the transmission signals transmitted from a transmission source at transmission timings at predetermined time intervals, at least one of the transmission timings shifted from the other timings in time; a complex reception signal generator adapted to generate complex reception signals based on the echo signals by performing quadrature detection on the echo signals; a phase calculator adapted to calculate a phase change amount, θ k, of the complex reception signals with respect to a reference phase based on a moving speed, V ANT, of the transmission source and a lapsed period of time, t k, from a reference timing, the phase change amount θ k being given by θ k = 4 ⁢ π V ANT t k / λ, with λ being the wavelength of the transmission signals; a phase corrector adapted to correct the phase of the complex reception signals based on the phase change amount, θ k, and outputting the corrected complex reception signals; and a Doppler processor adapted to perform Doppler processing on the corrected complex reception signals and outputting the Doppler-processed complex reception signals as Doppler echo signals of the object, wherein the phase calculator is further configured to receive a ground speed, V G, and a moving direction of the transmission source, to calculate the moving speed, V ANT, in an azimuth where the object exists, by using the received ground speed, V G, and the moving direction, and to output the moving speed, V ANT, to the phase calculator. an echo signal input unit adapted to receive echo signals resulted from transmission signals reflected on an object, the transmission signals transmitted from a transmission source at transmission timings at predetermined time intervals, at least one of the transmission timings shifted from the other timings in time; a complex reception signal generator adapted to generate complex reception signals based on the echo signals by performing quadrature detection on the echo signals; a phase calculator adapted to calculate a phase change amount, θ k, of the complex reception signals with respect to a reference phase based on a moving speed, V ANT, of the transmission source and a lapsed period of time, t k, from a reference timing, the phase change amount θ k being given by θ k = 4 ⁢ π V ANT t k / λ, with λ being the wavelength of the transmission signals; a phase corrector adapted to correct the phase of the complex reception signals based on the phase change amount, θ k, and outputting the corrected complex reception signals; and a Doppler processor adapted to perform Doppler processing on the corrected complex reception signals and outputting the Doppler-processed complex reception signals as Doppler echo signals of the object, wherein the phase calculator is further configured to receive a ground speed, V G, and a moving direction of the transmission source, to calculate the moving speed, V ANT, in an azimuth where the object exists, by using the received ground speed, V G, and the moving direction, and to output the moving speed, V ANT, to the phase calculator.