An intake manifold is provided and includes a runner that is connected between a plenum and a cylinder head to allow air introduced into the plenum to enter the cylinder head. A dent is formed at the runner such that the dent extends along a channel of the runner while having an inner surface with a protruding shape. The runner has, at an end thereof, an inner surface formed to be flat without being formed with the dent. The inner surface of the runner is connected to the cylinder head.