Disclosed is a high voltage relay having an enhanced air-tight structure, the relay including a molded case formed by molding a synthetic resin having an electric insulating property into a box shape having one open surface, an actuator accommodated in the lower molded case, and an arc extinguishing mechanism allowing insertion of a stationary electrode therein and installed on the actuator for covering the open surface of the molded case, the arc extinguishing mechanism including a gas discharge hole portion blocked when a thermosetting resin coated on the arc extinguishing mechanism for air-tightness is hardened.