INTERNAL COMBUSTION ENGINE

A bent section () is provided. An intake gas outlet (B) downstream of the bent section () is connected to an intake manifold (C). A throttle valve (A) is disposed in the vicinity of and upstream of an intake gas inlet (A) upstream of the bent section (). An EGR pipe () is connected to the bent section (). A rotation shaft () of the throttle valve (A) is provided so as to be perpendicular to a first plane () including an inlet side intake pipe axis (A) passing through the intake gas inlet (A) and an outlet side intake pipe axis (B) passing through the intake gas outlet (B). An outer surface, which is intersected by the first plane (), of the bent section () is formed to include a first sidewall surface (A) extending in parallel to the inlet side intake pipe axis (A) toward a bent side, a second sidewall surface (B) extending in parallel to the outlet side intake pipe axis (B) toward the bent side, and an outer curved surface (C) having a predetermined radius of curvature configured to connect bent side ends of the first sidewall surface (A) and the second sidewall surface (B).