An aspirator is provided that includes a nozzle that aspirates secondary air; a main body that forms a scroll-shaped airflow path on the outer circumference of the nozzle; a primary-air inflow path that tangentially communicates with the airflow path; and a diffuser that is connected to an open end of the main body and has a throat portion at which a tip portion of the nozzle is disposed. An inner wall of the primary-air inflow path, which communicates with the scroll-shaped airflow path, is offset outward from the center of the nozzle, and primary air introduced from the primary-air inflow path flows into the scroll-shaped airflow path from one direction.