Abstract: It is intended to provide an effective value impedance simulation method and apparatus in which even when an external circuit is opened or short-circuited, no infinite current or voltage occurs, no instability occurs in a numerical analysis, and the probability that a physical apparatus is broken is low. An instantaneous value/effective value conversion section connects a resistor and an externally controllable current source in parallel, measures an instantaneous value current i that flows through the parallel connection of the resistor and the current source, and converts the measured instantaneous value current i into an effective value current I. Another instantaneous value/effective value conversion section measures an instantaneous value voltage v that is applied to the parallel connection of the resistor and the current source, and converts the measured instantaneous value voltage v into an effective value voltage V.