The target searching device includes: a sound source which transmits a sound wave into a propagation space; a transducer array placed in an area to receive a forward scattering wave which scatters forward from the target within the propagation space; a subtraction processing device which subtracts a traveling wave directly traveling towards the transducer array from a mixed wave of the forward scattering wave and the traveling wave so as to separate the forward scattering wave; a passive-phase conjugate processing device which performs passive-phase conjugate processing on the forward scattering wave separated by the subtraction processing device so as to generate a passive-phase conjugated signal of the forward scattering wave; an autocorrelation processing device which performs autocorrelation processing on the traveling wave to generate an autocorrelation processed signal of the traveling wave; and a correlation device which judges a similarity between the autocorrelation processed signal and the passive-phase conjugated signal.