To enhance detection accuracy of an object as a target, while effectively reducing a clutter component, in a radio wave type object detector.

A clutter processing part 6 generates a processing-finished receiving signal with the clutter component removed therefrom, by calculating the difference between a receiving signal received by a reception antenna 3b, and a reference signal giving a waveform reference, when removing the clutter component in the receiving signal. The clutter processing part 6 sets the receiving signal, in the absence of the target. A signal processing part 7 detects the presence of the target, by comparing the current processing-finished receiving signal with the processing-finished receiving signal in the past.