A radar device for an automotive radar system includes a base, a first antenna module including a first transmitting antenna and a plurality of first receiving antennas for emitting a detection signal and generating a first signal receiving result, wherein the first antenna is fixed on the base, a second antenna module including a second transmitting antenna and a plurality of second receiving antennas for emitting the detection signal and generating a second signal receiving result, wherein the second antenna is fixed on the base, and a control system disposed in the base and coupled to the first antenna module and the second antenna module for outputting the detection signal to the first transmitting antenna and the second antenna and processing the first signal receiving result and the second signal receiving result.