PURPOSE: To obtain a sensor of high accuracy which economizes costly with melting point metals and has no variance in output by sticking the paste of high melting point metals into a required shape on a barlike core, further coating the outside circumference thereof with powder of ceramic raw materials and molding the same under pressure then calcining the molding.

CONSTITUTION: In the production of a ceramic sensor for measuring the density of O2 such as combustion gas, a material prepd. by forming paste 3 of high melting point metals such as paste of Pt into a required shape on a film prepd. by forming a self- adhesive layer 2 consisting of a butyral resin, etc. as well as a plasticizer and a solvent on a polyester film or the like 4 is wound on a bar-like core 1 having good release characteristic to stick the paste 3 thereon, then the film 4 is stripped therefrom. The outside circumference of the core 1 is coated with powder 6 of ceramic raw materials consisting of ZrO2 and Al2O3, etc. and the core is put in a rubber cylinder. After the core and cylinder are molded under pressure, the core 1 is removed, and paste 7 of Pt is coated into a required shape on the outside circumference of the molding and is calcined. Since the electrode is provided with a constant area and position by the use of a min. required amt. of the high melting point metallic paste for electrodes, the sensor of good accuracy having no variance in output is obtained.