A thermal type flow sensor, for measuring a flow rate of a fluid by means of a heat resistive element having a temperature dependency, comprising: a) a sensor element formed on a semiconductor substrate having a thin-walled portion therein including: • first and second heat resistive elements (6, 7) and temperature sensitive resistive elements (12a, 12b; 13a, 13b) formed on said thin-walled portion for outputting an electric signal corresponding to the flow rate of the fluid to be measured; • a first series circuit including at least said first heat resistive element and a second temperature sensitive resistive element; a second series circuit including at least a third temperature sensitive resistive element and a fourth temperature sensitive resistive element; a bridge circuit that connects the first series circuit and the second series circuit in parallel; all of said second to fourth temperature resistive elements (8, 9, 10) are formed at places outside said thin-walled portion on the semiconductor substrate; b) a driver circuit that takes in a first intermediate voltage between the first heat resistive element and said second temperature resistive element and a second intermediate voltage between said third temperature resistive element and said fourth temperature resistive element; characterized in that • said second heat resistive element is connected in parallel to said bridge circuit; • said second heat resistive element has a power consumption larger than that of the first heat resistive element, wherein the driver circuit supplies a heating current to both said heat resistive elements (6, 7); • said driver circuit controls a current that flows in the first and second heat resistive elements (7, 6) and said second to fourth temperature sensitive elements (8, 9,10) in accordance with a difference between those intermediate voltages. a) a sensor element formed on a semiconductor substrate having a thin-walled portion therein including: • first and second heat resistive elements (6, 7) and temperature sensitive resistive elements (12a, 12b; 13a, 13b) formed on said thin-walled portion for outputting an electric signal corresponding to the flow rate of the fluid to be measured; • a first series circuit including at least said first heat resistive element and a second temperature sensitive resistive element; a second series circuit including at least a third temperature sensitive resistive element and a fourth temperature sensitive resistive element; a bridge circuit that connects the first series circuit and the second series circuit in parallel; all of said second to fourth temperature resistive elements (8, 9, 10) are formed at places outside said thin-walled portion on the semiconductor substrate; • first and second heat resistive elements (6, 7) and temperature sensitive resistive elements (12a, 12b; 13a, 13b) formed on said thin-walled portion for outputting an electric signal corresponding to the flow rate of the fluid to be measured; • a first series circuit including at least said first heat resistive element and a second temperature sensitive resistive element; b) a driver circuit that takes in a first intermediate voltage between the first heat resistive element and said second temperature resistive element and a second intermediate voltage between said third temperature resistive element and said fourth temperature resistive element; • said second heat resistive element is connected in parallel to said bridge circuit; • said second heat resistive element has a power consumption larger than that of the first heat resistive element, wherein the driver circuit supplies a heating current to both said heat resistive elements (6, 7); • said driver circuit controls a current that flows in the first and second heat resistive elements (7, 6) and said second to fourth temperature sensitive elements (8, 9,10) in accordance with a difference between those intermediate voltages.