A ceiling-mounted indoor unit for an air conditioning apparatus is disposed in a ceiling of an air-conditioned room. The ceiling-mounted indoor unit includes a casing having an air outlet formed along a peripheral edge portion of an undersurface of the casing, at least four horizontal blades rotatably disposed in the air outlet, and a controller. The horizontal blades have airflow-direction angles that are independently changeable in an up-and-down direction. The control unit controls the horizontal blades such that at least two first horizontal blades of the at least four horizontal blades synchronously swing while taking the same posture. The first horizontal blades are adjacent to each other, and a combination of the at least four horizontal blades forming the first horizontal blades shifts in order along the peripheral edge portion.