An air sterilizing and purifying device of the present invention comprises: a closure shape casing that has an inlet and an outlet so as to receive contaminated indoor air into the casing and purify the air to be discharged and has a purifying chamber in which the contaminated air is purified； a fan motor installed in the casing in order to provide the inlet with a suction force and to move the contaminated air to the outlet through the purifying chamber； at least one filter installed in the inlet or the purifying chamber of the casing so as to remove particulate materials of the contaminated air； a photocatalyst module installed in the purifying chamber of the casing so as to come in contact with the contaminated air to sterilize and deodorize the contaminate air in the purifying chamber； and an ion cluster generating module installed in the purifying chamber while contacting the outlet of the casing and the photocatalyst module, so as to provide an ion cluster to the purified air discharged through the outlet. The photocatalyst module comprises: a sterilizing lamp that emits ultraviolet rays so as to sterilize the contaminated air； a tube shape photocatalyst filter that is spaced from the outer circumferential surface of the sterilizing lamp and is inserted in and connected with the sterilizing lamp along the length direction of the sterilizing lamp so as to come in contact with the contaminated air； and ring-shaped spacers coupled on the outer circumferential surface of the sterilizing lamp at regular intervals so as to form a space between the photocatalyst filter and the sterilizing lamp. The spacer and the photocatalyst filter are each formed as an oval cross section having a long axis in the direction of movement of the contaminated air so as to enlarge an air contact surface area that comes in contact with the contaminated air.본 발명은 오염된 실내공기가 케이싱 내부로 유입되어 정화된 상태의 정화공기가 배출되도록 흡입구 및 배출구를 가지며, 오염공기가 정화되는 정화실이 구비된 함체형의 케이싱； 상기 케이싱에 내장되어 상기 흡입구에 흡입력을 제공하면서 오염공기를
