PURPOSE: To impede the permeation of harmful liquid and the like positively in a simple and economical way by disposing a line hole part for accomodating a transmission line at least at one part around a water hole part and forming this line hole of impermeable molding core pipe material buried into a duct body.

CONSTITUTION: A line hole part 12 for accommodating the transmission line 20 of energy and information is disposed at the upper, lower, left-side or right- side part of a water hole part 11. The line hole part 12 is formed of the hollow part of an impermeable molding core pipe material buried into a duct body, that is, the inner surface of the line hole part 12 is enclosed along the whole periphery and length by the core pipe material. The core pipe material works effectively as an impermeable protecting casing body 50 for impeding the permea tion of harmful liquid and gas into the line hole part 12 from the soil around the water hole part 11 and a composite function duct 10, so that the transmis sion line 20 can be positively protected from corrosion and the like.