PURPOSE: To efficiently fetch sunlight, to remarkably reduce a cost and to increase safety, and to remarkably improve reliability by using a plastic optical fiber whose core and clad consist of plastic in a transmission line.

CONSTITUTION: The plastic optical fiber 2 whose core and clad consist of the plastic is used in the transmission line in a sunlight collection transmitter 1 which collects sunlight and irradiates collected light by transmitting to a prescribed place. The sunlight is transmitted on an optical cable 4 in which optical fibers 2 are bundled, and is radiated from an exiting end 5. A light guide for the sunlight is provided by connecting to the entering end of the plastic optical fiber 2, and the sunlight is entered into the light guide with heat resistance. The heat of the sunlight is diffused on the light guide, and the sunlight is made incident on the plastic optical fiber 2, however, the heat can be remarkably reduced. As the light guide, it is desirable to employ a material with superior permeability and superior connection efficiency with the plastic optical fiber 2 such as a glass rod, etc.