The sensor malfunction detection system for a gas-turbine engine is configured to determine or check once every first predetermined time period whether the outputted value from the sensor is within a permissible range and determines that the sensor is faulty when the result of the check is at least one result between the case of the number of times the outputted value is found not to be within the permissible range exceeding a first predetermined value and the case of the number of times the outputted value is consecutively found not to be within the permissible range exceeding a second predetermined value. Since the system discriminates whether the total number of times the sensor output is found to be outside the permissible range is fewer than the first predetermined value, it can avoid erroneous detection of transient abnormalities caused by noise or the like as sensor malfunction, and since it discriminates whether the number of times the sensor output is consecutively found not to be within the permissible range is fewer than the second predetermined value, it can promptly detect sensor malfunction owing to wire breakage or the like. The system can therefore detect sensor malfunction with good accuracy using a simple configuration.