Thermal type flowmeter

A thermal type flowmeter, comprising:

• a sensor portion conducting heating and temperature detection of a fluid contact portion in contact with a fluid flowing in a flow path;
• and
• a control portion controlling the heating and temperature detection conducted by the sensor portion,
• wherein the control portion measures a temperature rise time until a temperature of the fluid contact portion reaches an upper limit set temperature when heating the fluid contact portion and a temperature drop time until the temperature of the fluid contact portion reaches a lower limit set temperature when stopping heating the fluid contact portion, and calculates a time ratio based on the temperature rise time and the temperature drop time, and based on the calculated time ratio, converts a determined flow velocity into a flow rate value so as to perform flow rate determination via a sequence of flow rate conversion, and deviation reduction,
• wherein the control portion supplies the sensor portion with a superimposed current obtained by superimposing a detection pulse current for temperature detection supplied when heating and an applied current for heating that is continuously supplied, within the same cycle without switching.