To obtain stabilized amount of ventilation by a method wherein the number of rotation of an indoor fan is increased when an airflow direction regulating plate is set at a horizontal direction or a vertical direction.

When cooling operation or heating operation is started, two pieces of airflow direction regulating plates are pivoted and retained at a reference position (position whereat a ventilating resistance is minimized) or another position, newly selected and set by a remote controller (ST1). The airflow direction regulating plates are decided from the number of steps upon pivoting a stepping motor whether the plates are set horizontally or vertically (ST2). When the plates are set at a direction except horizontal or vertical directions, a ventilating fan 7 is operated with a set number of rotation (ST3). When the airflow direction regulating plates are decided that they are set at horizontal or vertical direction (ST2), the number of rotation of the indoor fan 7 is increased compared with the set number of rotation.