PURPOSE: To enable manufacturing an MOS type field-effect transistor wherein the spreading of a depletion layer to the region just under a gate electrode is little, the short channel effect can be restrained and the wiring resistance of the gate electrode is small, simplifying the product process, and reducing the products cost.

CONSTITUTION: A gate oxide film 1 is formed on the surface of a substrate 10 and a polysilicon film, e.g. is formed on the gate oxide film 1. A gate electrode 2 having a shape whose lower part is shorter than the upper part is formed by etching the polysilicon film selectively by using an ECR etching equipment. After that, first impurities are ion-implanted in the substrate 10 under the condition that the thick part of the gate electrode 2 is not penetrated but the thin part is penetrated, and a source and a drain 4a, 4b are formed on the surface of the substrate 10.