A beamforming device includes a sampler configured to sample a signal reflected from a focal point and received to a transducer array; a mixer configured to separate the sampled signal into an in-phase component signal and a quadrature component signal; a low pass filter configured to perform filtering on the in-phase component signal and the quadrature component signal; a decimator configured to perform decimation on the filtered in-phase component signal and quadrature component signal; a sampling delay compensator configured to compensate a sampling time delay based on a preset time delay resolution for the decimated in-phase component signal and quadrature component signal; a phase rotator configured to compensate a phase delay based on a preset phase resolution for the in-phase component signal and the quadrature component signal for which the sampling time delay is compensated; and a delay calculator configured to calculate a time delay resolution and the phase resolution, and to apply each to the sampling delay compensator and the phase rotator.