Ultrasonic flow rate measurement device includes measurement flow path in which a fluid to be measured flows, and a pair of ultrasonic vibrators that are disposed in directions such that a propagation path of an ultrasonic wave forms a V-shape relative to measurement flow path. Moreover, the device includes measurement circuit which measures a flow rate of the fluid to be measured by measuring a propagation time of the ultrasonic wave between the pair of ultrasonic vibrators, and inlet-side rectification part which is disposed, in the inlet side of measurement flow path, to stabilize the flow of the fluid to be measured. Furthermore, the device includes outlet-side coupling part which is disposed in the outlet side of measurement flow path, and signal lead-out part which outputs a flow rate value measured with measurement circuit.