GAS DETECTOR

PROBLEM TO BE SOLVED: To provide an on-vehicle gas detector which is prevented from being damaged with a simple structure in on-vehicle environment and allows normal operations to be hardly disturbed.SOLUTION: An on-vehicle gas detector X comprises a gas detecting element 10 which detects a gas to be detected, a casing 20 having an accommodation space 21 for accommodating the gas detecting element 10, and a gas permeable waterproof membrane 30 which is arranged at an introduction part 22 for introducing the gas to be detected to the gas detecting element 10 and allows the gas to be detected to pass through. A bridge part 40 arranged in the radial direction of an opening 23 of the introduction part 22 covers a portion of the gas permeable membrane 30 from outside the gas permeable membrane 30.