The present invention is to improve measurement accuracy of a thermal flow meter. In a thermal flow meter of the invention, a circuit package 400 includes a processing unit 604 in which a passage 605 and a circuit are disposed. An air flow sensing portion 602 is disposed in the passage 605. A fixing portion 372 is integrally formed with and fixed to the circuit package 400 and forms a bypass passage. The passage 605 of the circuit package 400 is arranged inside the bypass passage. In the bypass passage, a storage portion 384 having a concave portion 383 is formed to face the fixing portion 372. At least a part of the leading end 401 of the circuit package 400 is contained in the concave portion 383 of the storage portion 384.