PURPOSE: To enhance the performance by adding a gas collecting container to which a filter gas colliding plate is attached.

CONSTITUTION: In a gas collecting container 13 in which a gas flow-in port 14 opening area is larger than an opening area of a gas flow-outport 15 in opposite side, a gas collision plate 12 is integrally formed and through a connecting agent 16, a filter is secured. A gas collecting container 13 to which a gas colliding plate 12, a filter 11 is attached is attached to an end of a protecting pipe 5 to which an oxygen detecting element 6, an element heating heater 7 and an adiabatic material 8 are attached. Thus, the exhaust gas flowing from the gas flow-in port 14 is speed lowered by the gas colliding plate 12, thereafter, by positive pressure of an internal cavity 21, passes through the filter 11 and contacts the oxygen detecting element 6. Accordingly, the dust adhesion to the oxygen detecting element 6 and the clogging of the filter 11 are prevented to permit the long life and the response is enhanced by carrying out the gas replacement for a short time.