A capacitor simulation method and nonlinear equivalent circuit model enabling dynamic simulation of nonlinear characteristics when direct-current voltage is applied with high precesion are easily provided using a simple configuration. An equivalent circuit of a capacitor is represented using a series circuit of passive circuit elements. Characteristic change ratios of the passive circuit elements when a direct-current voltage is applied are expressed as an approximate function on the basis of an actually measured value. A reference voltage is referred to by control current sources connected in parallel to the passive circuit elements. The characteristic change ratios are calculated in accordance with the reference voltage Vref. Difference currents are generated on the basis of the characteristic change ratios and currents flowing when no direct-current voltage is applied, they are caused to flow concurrently with the currents flowing when no direct-current voltage is applied, and thus the nonlinear characteristics are simulated.