PURPOSE: To surely support a resin-made or steel pipe-made intake manifold, whose individual intake passage part is extended and curved to a downward side from an engine main unit of mounting the downstream end part of the intake passage part toward a collective part of connecting the upstream end part of the intake passage part, with sufficient supporting rigidity relating to the engine main unit.

CONSTITUTION: In a resin-made or steel pipe-made intake manifold 5, a plurality of individual intake passage parts 7 are respectively extended to curve to a downward side from an engine main unit 1 of mounting the downstream end part of the intake passage part toward a collective part 8 of connecting the upstream end part of the intake passage part, and one end part of a stay member 30 is mounted to the engine main unit 1 to engage the other end part of the stay member 30 with a throttle body mounting flange part 14 provided on a side of the collective part 8 in the intake manifold 5.