PURPOSE: To obtain a stable PTC element with large mechanical strength and less aging by adding SiO2 to a PTC ceramic composition for sintering.

CONSTITUTION: After adding SiO2 to a PbTiO3-TiO2 powder, stirred, mixed, and then molded, sintering is performed. SiO2 added at this time forms a solid solution with TiO2 and also functions as a binder for connecting the powders. Also, SiO2 covering a crystal grain prevents diffusion of O2 from the outside into a sintered body, thus eliminating instability of characteristics due to diffu sion of oxygen. Therefore, it is possible to obtain an element which is superb in mechanical strength and stability at the lapse of time.