RECTIFICATION STRUCTURAL BODY

A rectification structural body includes a pipe line configured such that air flows from an air cleaner to an airflow sensor. The pipe line has a portion bent in an arc shape. In the pipe line, an air guide plate dividing an internal space of the pipe line into an inner portion and an outer portion of the arc is provided substantially parallel with the center line of the pipe line. The air guide plate includes two ribs. The two ribs are each in an arc shape. The two ribs stand, inside the pipe line, facing each other to extend toward each other. End edges of the two ribs are separated from each other in a rib standing direction by 0.5 to 5 mm at least on an airflow sensor side of the pipe line.