This paper is devoted to the comparison of the numerically simulated Chua's circuit and the real circuit. The aim of the research was to figure out the factors affecting the computer simulation accuracy, and to find the ways to improve it. It was discovered that the most influence is exerted by an inaccuracy of the nonlinear Chua's diode characteristic measurement, a numerical integration method used for simulation and the operational amplifier properties. A possibility of an analog circuit application as a source of an accurate signal in order to find the most appropriate numerical method for the chaotic systems simulation is shown.