A semiconductor device fabrication method in which when a semiconductor device with a built-in light receiving element is fabricated, a section for dividing the light receiving element is protected from damage caused by, for example, etching. An antireflection coating is formed not only on a light receiving area in a divided photodiode area but on a division area including a junction area between a division section outside the light receiving area for dividing a photodiode and a cathode. A polycrystalline silicon film is formed so as to cover the antireflection coating. Accordingly, the antireflection coating on the junction area between the division section outside the light receiving area and the cathode is protected against, for example, etching by the polycrystalline silicon film. As a result, the appearance of a crystal defect, a change in impurity concentration, or the like is suppressed in this area. Therefore, a high-performance high-quality semiconductor device with a built-in photodiode can be fabricated.