Abstract: A thermal type flowmeter that can accurately perform flow rate determination at high speed and high precision even at low flow rate includes 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 heating and temperature detection conducted by the sensor portion. The control portion measures the temperature rise time until the temperature of the fluid contact portion reaches an upper limit set temperature when heating the fluid contact portion and the 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 based on the temperature rise time and the temperature drop time, converts a determined flow velocity into a flow rate value so as to perform flow rate determination.