Thermal flow meter with a circuit package having an air flow measurement circuit for measuring an air flow

A thermal flow meter comprising:

• 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 which senses a temperature of the measurement target gas by a temperature detection element;
• and
• a case which is provided with an external terminal outputting an electric signal indicating the air flow and an electric signal indicating the temperature of the measurement target gas and supports the circuit package, wherein
• the circuit package is structured such that the air flow measurement circuit and the temperature detecting portion are contained by resin, the circuit package has a protrusion which protrudes out of a circuit package main body, and the temperature detection element is buried in the protrusion, 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.