The noise power spectrum of a few high purity p-type InSb has been measured at 77°K. In general, it consists of the generation-recombination noise and the modulation noise. The magnitude of the former is proportional to p0-2, while the latter is proportional to p0-1, where p0 is the equilibrium concentration of the majority carriers. The purer the sample is, the more important is the generation-recombination noise. The magnitude and the power spectrum of the G-R noise are in accord with the present theory. The lifetime τ of the majority carriers can be obtained from the G-R noise power spectrum; it is found that τp0 = 1.1×109sec/cm3.