The present invention relates to a wind direction informing device composed by a wind direction indicating device and a wind direction displaying circuit, wherein the wind direction indicating device includes a wind vane, a chassis and a small shaft. One end of the wind vane shows an arrow shape and the other end of the wind vane shows a wing shape, and the underpart of the arrow-shaped end contains a small magnet, wherein the small magnet is connected with the arrow-shaped end; and the underpart of the chassis contains eight Hall elements evenly arranged on the circumference of the chassis in eight directions, i.e., east, west, south, north, northeast, southeast, northwest and southwest. According to the operating principle of the Hall element, it is known that once the Hall element contacts with a magnetic field, the Hall element can output a voltage, so that when the small magnet on the wind vane contacts any one of the Hall elements in any direction, the Hall element in that direction outputs a voltage, wherein the voltage enables the corresponding light emitting diode to illuminate through the displaying circuit, and thereby the wind direction can be determined by merely observing the orientation of the luminous LED indoors.