a compound chemically sensitive element comprises a chemically sensitive assembly which is selectively sensitive to a specific ion or a specific substance in a material to be examined , and a ph sensor having an insulated gate field effect transistor structure , both of which are separately manufactured . the chemically sensitive assembly and the insulated gate of the ph sensor are electrochemically connected together by a conductive resin , thus improving the durability and the selectivity of the element . in this manner , limitations imposed upon the manufacture of mos ph sensor is removed , permitting a wide variety of chemically sensitive films to be used .