The present invention relates to an intake manifold for a vehicle and comprises tanks for stabilizing intaken air introduced from a throttle body; a plurality of zip tubes diverged from the tanks; a plurality of runners connected to the zip tubes and communicated with respective cylinders; and a adjustment apparatus provided at one side of the zip tubes and the runners for varying the diameter of the zip tube and the diameter of the runner according to an engine operation range. Due to the above structure, the diameter of the zip tube and the diameter of the runner can be varied continuously within the overall operating range of an engine by the adjustment apparatus. Hence, the performance of the engine can be enhanced.