PURPOSE: To obtain a high quality sensor with a higher reliability, by a method wherein a sensor section is covered entirely with a water-proof adhesive after being held down with a fluorine-based rubber rod to mask and the rubber rod is removed before or after the solidification of the adhesive.

CONSTITUTION: A printed circuit board 7 has a wire pattern 8 with a sensor section 5 at one end, and a pattern 8' at the other end to be connected to a measuring apparatus. An adhesive 13 is quite the same as an adhesive 9 and protects a wire 10 bonded on the circuit board 7 after a sensor chip 6 is fastened thereon while preventing the leaking. When the adhesive 13 is heaped up, it is made entirely to cover the sensor section 5 pressing a fluorine-based rubber rod 12 at a position thereof. When the rubber rod 12 is withdrawn after the solidification of the adhesive, the condition is as shown by (b) and when withdrawn before the solidification of the adhesive, it runs a little as shown by the (d), but there is no problem in the application. The adhesive can be put tight during the pressing of the rubber rod 12 and the rubber rod 12 can be withdrawn simply without adhering thereto.