For the purpose of analyzing noise characteristics of a very low-level dc current amplifier using a high-ohmage resistor negative feedback circuit, we made some noise sources in the form of the electronic circuit simulation program PSpice with the C language program and simulated transient analyses of the very low-level dc current amplifier using the PSpice. As a result, it was observed that in terms of rise time and increases in the amplitudes of the noise voltage with or without positive feedback circuit, the behavior of output waveform of the simulated equivalent circuit was similar to that of the experimental circuit.