<p>A hydrogen gas sensor of contact combustion type that not only has a simple structure but also is capable of suppressing the occurrence of sensitivity deterioration even in the presence of a silicon compound being a catalyst poisoning substance over a prolonged period of time. The hydrogen gas sensor has detection element (1) including sensitive part (2) and silicon trap layer (3). The sensitive part (2) has the capability of being heated by Joule heat brought about by current passage, the capability of, upon being heated, burning hydrogen gas and the capability of producing a change of electrical resistance in accordance with a temperature rise attributed to hydrogen gas combustion heat and outputting the change of electrical resistance as a detection signal for hydrogen gas concentration. The silicon trap layer (3) covering the sensitive part (2) contains a silicon trap substance capable of trapping any silicon compound from a gas passing through the silicon trap layer (3).</p>
