A precision analog simulator for a Josephson junction has been developed. This simulator is composed of several unit circuits and its sources of the error are tractable. The term corresponding to sin&fgr; is generated by an integrator with a resetting switch and a sinusoidal function generator. The time dependence of junction voltages and theI–Vcharacteristics are obtained for a current driven Josephson junction and compared with the analytical solutions for nonhysteretic case. The sources of the error are investigated in this simulator. In order to simulate quasiparticle conductance, an adjustable nonlinear resistance network was also constructed.