PURPOSE: To provide a MOS field effect transistor, which has a stable gate insulating film thin in effective thickness and advantageous for micronization of the transistor and capable of being driven with high voltage by removing the warp of a semiconductor wafer and crystal defects, and its manufacture.

CONSTITUTION: A MOS field effect transistor has a pair of diffused layers 2 of second conductivity type formed a specified distance L equivalent to a channel region apart on a first conductivity type of semiconductor substrate 1, and, on a channel region made between these diffused layers 2 in a pair, a gate insulating film 8 constituted of the laminate structure, where a lower silicon oxide film 3, a silicon nitride film 4, and an upper silicon oxide layer 5 are formed in order, and a gate electrode being made on the gate electrode 8.