The present invention relates to a sensor element for detecting hydrogen chloride (HCl) gas, a sensor device having the sensor element, and a method of manufacturing the sensor element, wherein the sensor element includes: an ionic layer including a Ag ion obtained through ionization; an ion conductive layer, in which the Ag ion is conducted, the ion conductive layer being formed on the ionic layer; and a reactive layer, in which the Ag ion conducted from the ion conductive layer and HCl gas react with each other, the reactive layer being formed on the ion conductive layer. The sensor element detects HCl gas generated from insulting materials when fire occurs, thereby detecting an electrical fire and preventing gas and fire spreading.