A new numerical calculation method of the deconvolution specialized for the linear compartment analysis of pharmacokinetics was presented. In this method, the deconvolution was carried out from numerical data of precursor obtained directly in unequal interval of time and an empirical exponential equation for successor. From the assumption for the integrated weight function to be simple increasing function, the divergence of calculation was protected completely. In the experiment of model calculation, the accuracy and the precision were proved to be practically sufficient for pharmacokinetic studies.