A circuit simulation apparatus according to an embodiment of the present invention calculates a set value of a SPICE parameter of a MOSFET to carry out a variation analysis on a semiconductor circuit including the MOSFET. The apparatus includes a storage part configured to store an intermediate model expression that includes a variable related to a manufacture condition or device structure of the MOSFET as a variable affecting variation characteristics of the MOSFET, the intermediate model expression being formed with a universal function having a physical correlation between a physical amount defined by the variable and the SPICE parameter, a setting part configured to set information about the variable included in the intermediate model expression, a calculation part configured to calculate the set value of the SPICE parameter by using the information set in the setting part and the intermediate model expression stored in the storage part, and an output part configured to output process variation dependency of the semiconductor circuit.