A flow measurement device includes a flow sensor that senses a flow rate of a measurement target fluid flowing through a main channel, a characteristic-value obtaining unit that includes a heater heating the target fluid and a temperature sensor sensing a temperature of the target fluid, and obtains a characteristic value of the target fluid, and a flow rate correction unit that corrects a flow rate of the target fluid calculated based on a sensing signal from the flow sensor using the characteristic value of the target fluid obtained by the characteristic-value obtaining unit. The heater and the temperature sensor are arranged parallel to each other in a direction orthogonal to a flow direction of the target fluid. The characteristic-value obtaining unit obtains the characteristic value based on a difference between the temperatures of the target fluid sensed by the temperature sensor before and after the heater temperature is changed.