PURPOSE: To provide a thermosensitive flow rate sensor which is excellent in measuring response with a construction allowing holding of a lead pin easily and accurately without damaging a plate-shaped thermosensitive resistor with a limited thickness.

CONSTITUTION: Parts 2a and 3a where signal fetching electrodes of plate-shaped thermosensitive resistors 2 and 3 are inserted into a slit 6 formed on a lead pin 4 to hold the plate-shaped thermosensitive resistors 2 and 3 on the lead pin 4 while the plate-shaped thermosensitive resistors 2 and 3 are connected electrically to a control circuit through the signal fetching electrode and the lead pin 4.