Rectification structural body

A rectification structural body comprising:

• an inlet port into which air from an air cleaner flows;
• an outlet port from which air flows out toward an airflow sensor;
• and
• a chamber provided between the inlet port and the outlet port, wherein
• the inlet port and the outlet port are provided in such directions and at such positions that an air flow is bent in the chamber,
• the chamber includes two cases of a first case and a second case, the chamber being divided into the two cases,
• a substantially arc-shaped first rib is provided to protrude from the first case,
• an end portion of the first rib is apart from the second case,
• a substantially arc-shaped second rib is provided to protrude from the second case,
• the second rib is provided substantially parallel to the first rib to overlap with the first rib with a predetermined spacing, and
• the first rib and the second rib form, in the chamber, a flow path wall such that a flow of air flowing into the chamber through the inlet port curves and directs toward the outlet port.