A vehicular radar includes a transmitter for outputting a transmitted electromagnetic wave; an antenna unit for radiating the transmitted electromagnetic wave and receiving a electromagnetic wave reflected by an object to be detected as a received electromagnetic wave; a receiver for detecting the reflected electromagnetic wave received by the antenna unit; and a signal processor for processing an output signal from the receiver to output information about the object. The antenna unit includes a single electromagnetic radiator for radiating the transmitted electromagnetic wave, a single reflector for reflecting the transmitted electromagnetic wave from the electromagnetic radiator and radiating the transmitted electromagnetic wave as a beam, and a reflector swinging device for swinging the reflector so as to successively change a direction of the beam. The reflector swinging device includes a first arm, a second arm, a swinging pivot, a cam and a cam follower.