Abstract: A ceiling panel structure (10, 310) is mounted on a ceiling surface (201) downstream of an air-outlet (211) of a ceiling-mounted air-conditioning apparatus (indoor unit) (200) having an air-inlet (210) at a central portion and the conditioning air-outlet (211) at a peripheral portion. The ceiling panel structure minimizes the smudging of the ceiling surface, and is applicable even to the pre-mounted or existing air-conditioning apparatus. The ceiling panel structure (10, 310) can be mounted on the ceiling surface (201) outside of the air-conditioning apparatus (200), and has a deflection induction portion (47, 347) substantially rigid against the airflow to deflect a part (S1, S2) of the conditioning air blown out through the air-outlet (211) of the air-conditioning apparatus (200) back to the room air-inlet (210).