PURPOSE: To increase transfer capacity and to prevent a fault due to a lightning stroke, etc., by installing a flexible protective tube into which an optical fiber for transmitting an optical signal between a control part of an oil feeding device and an input/otput part of an information processor has been made to pass through, in a slackened state, in a groove.

CONSTITUTION: In an oil station, a groove 22 is formed by cutting a floor between an oil feeding device and an oil feeding information processor installed in a plate being at a distance from said device. A flexible protective tube 24 into which an optical fiber 19 for transmitting an optical signal between a control part of the oil feeding device and an input/output part of the information processor has been made to pass through, in a slackened state is installed in this groove 22. Subsequently, the protective tube 24 is fixed by filling the groove 22 with a restoring material 25 such as cement mortar, epoxy mortar, etc. In this way, after the optical fiber has been laid, even if a crack of the floor, etc. occur, they are absorbed by the protective tube, and cut of the optical fiber is prevented.