Among various types of harmful gases, hydrogen sulfide is a strong toxic gas that is mainly generated during spillageand wastewater treatment at industrial sites. Hydrogen sulfide can irritate the conjunctiva even at low concentrations of lessthan 10 ppm, cause coughing, paralysis of smell and respiratory failure at a concentration of 100 ppm, and coma and permanentbrain loss at concentrations above 1000 ppm. Therefore, rapid detection of hydrogen sulfide among harmful gasesis extremely important for our safety, health, and comfortable living environment. Most hydrogen sulfide gas sensors thathave been reported are electrical resistive metal oxide-based semiconductor gas sensors that are easy to manufacture andmass-produce and have the advantage of high sensitivity; however, they have low gas selectivity. In contrast, the electrochemicalsensor measures the concentration of hydrogen sulfide using an electrochemical reaction between hydrogen sulfide,an electrode, and an electrolyte. Electrochemical sensors have various advantages, including sensitivity, selectivity, fastresponse time, and the ability to measure room temperature. However, most electrochemical hydrogen sulfide gas sensorsdepend on imports. Although domestic technologies and products exist, more research is required on their long-term stabilityand reliability. Therefore, this study includes the processes from electrode material synthesis to sensor fabrication and characteristicevaluation, and introduces the sensor structure design and material selection to improve the sensitivity and selectivityof the sensor. A sensor case was fabricated using a 3D printer, and an Ag reference electrode, and a Pt counterelectrode were deposited and applied to a Polytetrafluoroethylene (PTFE) filter using PVD. The working electrode was alsodeposited on a PTFE filter using vacuum filtration, and an electrochemical hydrogen sulfide gas sensor capable of measuringconcentrations as low as 0.6 ppm was developed.