In a radar device installed in a vehicle for detecting a target around the vehicle, a transmitter transmits a plurality of radio signals at intervals. A scanning mechanism is arranged such that each of the plurality of radio signals is individually entered thereto. The scanning mechanism is swingable relative to the transmitter to change a direction of each of the plurality of radio signals entered thereto, thus scanning each of the plurality of radio signals over an angular scanning field. The angular scanning field is located around the vehicle. A receiver receives a plurality of reflected signals to detect intensities of the plurality of received reflected signals. At least some of the plurality of reflected signals are generated based on reflection of at least some of the plurality of radio signals from the target.