The insulated gate bipolar transistor(IGBT) has negative Miller capacitance during switching transients. It has conventionally been attributed to the voltage dependency of the Miller capacitnce. However this explanation has physical ambiguity, yet, it lacks a discussion of the conditions for the occurrence of negative Miller capacitance as well. We argue that it is the current dependence to the Miller capacitance that results in the negative case. In this paper, we provide a modification.