PURPOSE: To obtain a micro gas sensor for detecting the kind or concentration of gas, as well as leakage regardless of presence/absence of gas flow which can be mass produced at low cost.

CONSTITUTION: The micro gas sensor comprises a silicon substrate 1 having a recess formed by semiconductor fabrication technology to open downward, a gas detecting part formed on the surface of the diaphragm structure of the silicon substrate corresponding to the recess by semiconductor fabrication technology, and a windbreaker for protecting the gas detecting part against the gas flow. The windbreaker is windbreak walls 7a, 7b or a windbreak hood formed or jointed on the silicon substrate 1 in the vicinity of gas detecting part so that the gas flow does not strike directly against the gas detecting part.