In a semiconductor device including a protection diode for preventing electrostatic breakdown employing a low capacitance protection diode, an occupation area of a Zener diode as a voltage limiting element is not needed on a front surface of a semiconductor substrate. A P+ type embedded diffusion layer is formed in a P+ type semiconductor substrate. This is then covered by a non-doped first epitaxial layer. A high resistivity N type second epitaxial layer is then formed on the first epitaxial layer. The second epitaxial layer is divided by a P+ isolation layer into a first protection diode forming region and a second protection diode forming region. An N+ type embedded layer extending from the front surface of the first epitaxial layer of the first protection diode forming region to the first epitaxial layer and the second epitaxial layer, and so on are then formed. A Zener diode is formed by a P+ type upward diffusion layer extending from the P+ type embedded diffusion layer and the N+ type embedded layer.