An indoor unit of an air-conditioning apparatus includes an air-sending device unit having an air-sending device unit housing configured to house an air-sending device and provided with an air inlet; and a heat exchanger unit having a heat exchanger unit housing configured to house an indoor heat exchanger, provided with an air outlet, and configured to be coupled to the air-sending device unit housing, wherein the air-sending device includes a rotating fan, an electric motor, and a casing, the casing, the air inflow port, and the air-sending device unit housing, a first rail unit, and a slide member.