A high-temperature resistance is disposed in an internal passage and has its energization controlled based on an intake-air flow rate in the passage to increase/decrease a heat generation amount. A first low-temperature resistance constitutes a bridge circuit which has its energization state changed according to the heat generation amount of the high-temperature resistance. The first low-temperature resistance varies its resistance value according to intake-air temperature. A second low-temperature resistance is an element, which is not incorporated into the bridge circuit and varies its resistance value according to intake-air temperature to increase/decrease an energization amount. The second low-temperature resistance is provided on a substrate. Another bridge circuit produces an intake air amount detection signal using an electrical signal generated by operation of the high-temperature resistance and the first low-temperature resistance. A digital circuit uses an electrical signal produced by the second low-temperature resistance as an intake temperature detection signal.