To provide a device for cleaning the indoor air by efficiently utilizing the sunlight.

In a solar air cleaning device, a hollow cylinder having a light receiving face made of a light transmitting material is installed outdoors, a lower part and an upper part of this hollow cylinder comprise the vent holes 3, 4 communicated with the indoor, and a photocatalyst element 1 is mounted inside of the hollow cylinder oppositely to the light receiving face. By applying this structure, the inside of the cylinder is warmed by the sunlight, and the ascending air current generates, whereby the indoor air is circulated in the cylinder. The odor components and the harmful matter such as nitrogen oxide or the like included in the air circulated in the cylinder, are adsorbed by the photocatalyst element 1, and the adsorbed harmful matter is oxidized and decomposed into the water molecule, carbon dioxide or the like by the optical activating action of the photocatalyst when the photocatalyst element is exposed to the sunlight.