Disclosed is a micro sensor. Particularly, a first sensor electrode is provided on a first side of a substrate, a second sensor electrode is provided on a second side of the substrate, and the substrate is provided with an etching hole penetrating from the first side to the second side of the substrate. A sensing material provided between the first sensor electrode and the second sensor electrode is inserted in the etching hole. When detecting gas, the micro sensor can minimize influence of moisture in air.