A gas alarm for detecting a target gas based on a resistance value of a sensor element comprises a measuring unit to measure a characteristic value of the sensor element, a heating control unit to control a heater to perform a heating process to heat the sensor element, a determining unit to determine, based on the characteristic value, whether the sensor element is in a blunt state in which sensitivity of the sensor element is decreased, and an aborting control unit to abort the heating process to determine whether the sensor element is in the blunt state when a characteristic value of the sensor element measured by the measuring unit after beginning of the heating process by the heating control unit meets a predetermined condition.