A sheet-manufacturing device that manufactures a sheet of which the quality is stable, by controlling airflow to be constant and causing a defibrated state to be constant. A sheet-manufacturing device including a defibrating unit configured to generate a defibrated material by defibrating a defibration object; a temperature acquiring unit configured to acquire a temperature of the defibrating unit; and a control unit configured to change a mass flow rate of the air including the defibrated material transported from the defibrating unit.