Provided are a flowrate measurement device and a flowrate measurement method. The flowrate measurement device includes an attachment portion configured to attach the flowrate measurement device to an object to be measured, and a measurement portion. The measurement portion includes a first ultrasonic transmitter, a second ultrasonic transmitter and a plurality of signal receivers between the first ultrasonic transmitter and the second ultrasonic transmitter. The plurality of signal receivers are spaced apart from each other. The first ultrasonic transmitter, the second ultrasonic transmitter and the plurality of the signal receivers are all disposed on the attachment portion, such that both the first ultrasonic transmitter and the second ultrasonic transmitter are capable of emitting an ultrasonic wave signal to the object to be measured. The signal receivers are capable of receiving an ultrasonic wave signal reflected from the object to be measured.