An indoor unit for an air-conditioning apparatus includes a box-shaped casing having an air inlet in a top surface of the casing and an air outlet in a bottom surface of the casing, an air-sending device disposed in the casing and configured to suck in indoor air through the air inlet and blow conditioned air through the air outlet, a heat exchanger disposed in the casing and configured to cause the indoor air to exchange heat with refrigerant to supply the conditioned air, a vertical deflector, a first auxiliary vertical deflector, and a second auxiliary vertical deflector each rotatably arranged in the air outlet and configured to change an air flow direction in a vertical direction.