A thermal type flow sensor measures a flow rate of a fluid by means of a heat resistive element having a temperature dependency. The sensor is comprised of: plural heat resistive elements used for a flow rate measurement; and a driver circuit for controlling a current applied to these heat resistive elements to cause their heating. The driver circuit is configured to sense a resistance change of a lower-temperature side heat resistive element among the plural heat resistive elements and to control the current to be applied to the plural heat resistive elements in accordance with a sensed value of the lower-resistance's variation.