PURPOSE: To attain sure optical communication without requiring so much accuracy for the directivity of transmission/reception by applying optical communication between a satellite head possible for transmission/reception of light in all directions of surrounding and a terminal head whose transmission/reception direction is unidirectional.

CONSTITUTION: Plural light emitting elements are mounted in a hole 15 of a heat sink 14 fixed to a brachet 13 in the inside of a semispherical cover 6 tixed to a ceiling face 40 in a room, the light emitting element is mounted on a printed board 16 so that the light is transmitted to the entire surrounding at the outside of a cover 6. A photodetector 11 is fitted to a retainer in the direction of the surrounding 4 of the cover 6 and a rubber cover 12 preventing the detour of the light from the light emitting element in the inside is provided under the retainer while being adhered closely on the inside face of the cover 6 to constituted a satellite head 41. In performing optical communication between the satellite head 41 and the terminal head 42 provided with the light emitting element and photodetector in one direction, the sure optical communication is performed surely even if no strict accuracy exists in the directionality of the head 42.