The present invention relates to a ventilation-fan airflow measurement device for livestock barns, and more specifically, to a device for measuring the airflow of a livestock ventilation fan. The device is installed corresponding to one side of the ventilation fan, and when the fan operates, a moving bar is configured to move from one side to the other within an air-movement space generated by the fan. A plurality of hot-wire airflow sensors are installed along the longitudinal direction of the moving bar, so that the airflow per unit area within the air-movement space can be measured. This enables accurate measurement of the airflow rate of the livestock ventilation fan as well as measurement of the ventilation capacity according to the operating rate of the fan.