The radar system includes: a transmission circuit transmitting the radar waves via a transmission antenna; a receiving circuit receiving the reflected waves via a receiving antenna; a delay line having an end connected to aid transmission circuit and the other end connected to said receiving circuit, which delays the radar waves by a predetermined delay amount; a correlation circuit/coherent detection circuit which detects a waveform having a strength equal to or higher than a predetermined strength, from a signal provided from said receiving circuit which obtains the signal from the reflected waves or the delayed radar waves; and a level decision circuit which judges, during self-diagnosis, whether or not the detected waveform is a waveform of the delayed radar wave according to the predetermined delay amount, and if the waveform is not the waveform of the delayed radar wave, determines that abnormality occurs in said radar system.