A radio detection and ranging (radar) signal processing device obtains radar data by compensating for a change in a carrier frequency of a sensed radar signal, and outputs a radar image map based on the obtained radar data. The radar signal processing method includes obtaining a beat frequency signal based on a radar transmission signal generated based on a frequency modulation model and a radar reflection signal obtained from the radar transmission signal being reflected from an object, and generating radar data by compensating the beat frequency signal for a carrier frequency change by the frequency modulation model.