In a semiconductor device, a first conductive film made of, for example, polysilicon is formed on the element region of the semiconductor substrate. An insulation film is formed on the semiconductor substrate, for covering at least the first conductive film. A second conductive film covers at least the end portion of the insulation film. The first conductive film is used as a gate electrode of the MOS transistor, and the second conductive film is used as a protection film for covering and protecting the end portion of the insulation film and a lead-out electrode of the bipolar transistor. The end portion of the insulation film is covered and protected by the second conductive film obtained by patterning the conductive layer made of, for example, polysilicon. Further, the conductive layer is patterned so that stepped portions formed on the insulation film and the end portion of the insulation film are covered, and using this pattern, anisotropic etching is carried out. Thus, formation of residue on the side-wall of the second conductive film, on the stepped portions formed as covering the first conductive film, can be avoided. In a later step, the pattern of the second conductive film which covers the stepped portion is removed by etching.