An air blowing device has a first blowing portion, a duct, and an airflow causing member. The first blowing portion has a guide surface and is provided with a first blowing outlet that blows air from a blower unit into a vehicle compartment. The airflow causing member defines at least one of a first passage and a second passage located on one side and an other side of the airflow causing member in a front-rear direction of a vehicle respectively in the duct. The airflow causing member sets a first condition in which a high-velocity airflow flows in the first passage and a low-velocity airflow flows in the second passage by decreasing a sectional area of the first passage to be smaller than a sectional area of the second passage. The high-velocity airflow flows along the guide surface and is blown into the vehicle compartment.