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. During a cooling operation, the first auxiliary vertical deflector is positioned on a side of a front surface of the casing, a downstream end of the first auxiliary vertical deflector is positioned below the bottom surface of the casing, the second auxiliary vertical deflector is positioned below the first auxiliary vertical deflector, and an upstream end of the second auxiliary vertical deflector is positioned above the vertical deflector.