To provide a wiring/piping duct having a freely bent structure at low costs without increasing the number of part items or lowering strength.

A wiring/piping duct is provided with a cover section 5 extended in the longitudinal direction and bent in the width direction and flange sections 6 and 6 continuous in the sides of the cover section 5, and adapted to house a pipe or a line to be set in the cover section 5. This duct is constructed by molding a plate body made by laminating an upper layer part 2 made of a hard resin and a lower layer part 1 made of a soft resin in this shape, and a plurality of horizontal grooves 3,..., are formed at least in a part of the upper layer part 2 in the longitudinal direction.