An intake system piping structure of an internal combustion engine includes an intake manifold connected to an end-side first cylinder and an end-side second cylinder which are provided farthest from each other in a cylinder bank in which a plurality of cylinders is placed in line, and an intercooler connected to the intake manifold. The intercooler is arranged in such a manner that a widthwise center of the intercooler on the side of an intake inlet and a widthwise center of the intercooler on the side of the manifold are offset to the side of the end-side second cylinder from a cylinder bank direction center line in center between an axial center line of the end-side first cylinder and an axial center line of the end-side second cylinder. Furthermore, the intercooler is also arranged in such a manner that an offset amount of the widthwise center of the intercooler on the side of the intake inlet from the cylinder bank direction center line is greater than an offset amount of the widthwise center of the intercooler on the side of the manifold from the cylinder bank direction center line.