To provide an in-vehicle radar apparatus whose measurement error is made small by improving a time response property, even in the case that a state of a target significantly varies in a short time.

The in-vehicle radar apparatus employs two processing sections of one FFT. A first FFT processing section executes a fast Fourier transform (FFT) for a plurality, M, of beat signals. A second FFT processing section executes a fast Fourier transform (FFT) for a plurality, L, of beat signals, wherein L is smaller than M. When the amount of temporal variation in a peak signal is small, a distance, an angle and a relative velocity about the target are calculated by using a peak signal obtained from a frequency analysis performed by the first FFT processing section which has an excellent S/N property. When the amount of temporal variation in the peak signal is large, the distance, the angle and the relative velocity about the target are calculated by using a peak signal obtained from a frequency analysis performed by the second FFT processing section which has an excellent response property.