A thermal flow meter has a bypass passage for taking in and flowing measurement target gas flowing in a main passage, a circuit package having an air flow measurement circuit for measuring an air flow by carrying out heat transfer in relation to the measurement target gas flowing in the bypass passage, and a temperature detecting portion. A case is provided with an external terminal outputting electric signals indicating the air flow and the temperature of the measurement target gas and supports the circuit package. Resin contains the air flow measurement circuit and the temperature detecting portion. The temperature detecting portion has a protrusion which protrudes out of a circuit package main body, and the protrusion is formed into a shape which is thicker in its root than in its leading end portion and its neck portion is narrower little by little toward the leading end.