The receiving apparatus of a spotlight mapping radar system is provided with a digital beamforming antenna capable of converting the echo signals received by a plurality of antenna elements into corresponding digital signals and processing them by DFT and forming a plurality of reception beams oriented in different directions at the same time to enhance the cross-range resolution without reducing the distance measurement capability and the measurable range. Pulse compressors, azimuth compressors, display buffers and reference signal generators are provided respectively for each of the outputs of the digital beamforming antenna for outputting the plurality of reception beams. An output picture synthesizing apparatus synthesizes signals representing the picture information from the respective display buffers and outputs the synthesized signals to a display to display thereon the synthesized picture of an object to be observed.