In a flow meter device of the present invention, a time measuring section of the flow meter device includes a first counter which starts counting at a starting point of measurement of propagation time; and a second counter which starts counting at an end point of the measurement of the propagation time, and performs counting at a higher speed than the first counter. A propagation time TO is finally obtained by subtracting time Δt which is measured by the second counter and passes from the end point until the first counter counts up, from time T which is measured by the first counter and passes from a starting point until the first counter counts up after the end point. A flow calculating section calculates a flow with high accuracy using the propagation time TO. Thus, lower electric power consumption can be achieved, and accuracy of measurement of flow can be improved.