An indoor unit of an air-conditioning apparatus, comprising: a casing having an air inlet and an air outlet that are provided as openings formed in a lower surface portion of the casing; a fan housed in the casing and configured to suck air in an air-conditioned space from the air inlet into the casing and blow the air from the air outlet; a heat exchanger housed in the casing and configured to cause heat exchange to be performed between refrigerant that flows in the heat exchanger and the air sucked into the casing; and a lateral airflow adjusting unit configured to adjust in a lateral direction, an angle of the air that is blown from the air outlet, wherein in the casing, a suction flow passage (4, 14, 24, 34) and a blowout flow passage (5, 15, 25, 35) are provided, the suction flow passage (4, 14, 24, 34) causing the air inlet and the heat exchanger to communicate with each other, the blowout flow passage (5, 15, 25, 35) causing the heat exchanger and the air outlet to communicate with each other, the lateral airflow adjusting unit includes a plurality of lateral airflow adjusting plates arranged in the blowout flow passage (5, 15, 25, 35) at defined intervals in the lateral direction, and a drive device including a drive motor and configured to swing the plurality of lateral airflow adjusting plates with power generated by the drive motor, characterised in that the casing includes an accommodating chamber that is isolated from the blowout flow passage (5, 15, 25, 35) and communicates with the suction flow passage (4, 14, 24, 34), and the drive motor is accommodated in the accommodating chamber. a casing having an air inlet and an air outlet that are provided as openings formed in a lower surface portion of the casing; a fan housed in the casing and configured to suck air in an air-conditioned space from the air inlet into the casing and blow the air from the air outlet; a heat exchanger housed in the casing and configured to cause heat exchange to be performed between refrigerant that flows in the heat exchanger and the air sucked into the casing; and a lateral airflow adjusting unit configured to adjust in a lateral direction, an angle of the air that is blown from the air outlet, wherein in the casing, a suction flow passage (4, 14, 24, 34) and a blowout flow passage (5, 15, 25, 35) are provided, the suction flow passage (4, 14, 24, 34) causing the air inlet and the heat exchanger to communicate with each other, the blowout flow passage (5, 15, 25, 35) causing the heat exchanger and the air outlet to communicate with each other, the lateral airflow adjusting unit includes a plurality of lateral airflow adjusting plates arranged in the blowout flow passage (5, 15, 25, 35) at defined intervals in the lateral direction, and a drive device including a drive motor and configured to swing the plurality of lateral airflow adjusting plates with power generated by the drive motor, characterised in that a plurality of lateral airflow adjusting plates arranged in the blowout flow passage (5, 15, 25, 35) at defined intervals in the lateral direction, and a drive device including a drive motor and configured to swing the plurality of lateral airflow adjusting plates with power generated by the drive motor, characterised in that the casing includes an accommodating chamber that is isolated from the blowout flow passage (5, 15, 25, 35) and communicates with the suction flow passage (4, 14, 24, 34), and the drive motor is accommodated in the accommodating chamber.