PURPOSE: To improve the output of an internal combustion engine in its full speed range by rotatably arranging in the border of an inlet chamber on an intake passage a rotor shaft drilling a through hole penetrating through a diametric direction and opening and closing in a specific condition.

CONSTITUTION: A variable intake device 5 arranges a device main unit 7, forming an inlet chamber 6 in one side part of an intake passage 4, forming a principal part. A rotor shaft 8 is rotatably arranged in the upstream side of a location facing to the intake passage 4 of the inlet chamber 6. While the rotor shaft 8 additionally provides an inlet valve 9 cutting off a communication opening part between the inlet chamber 6 and the intake passage 4. Further the rotor shaft 8 is provided with a through hole 10 drilled toward the diametric direction. Here the through hole 10 is closed in a low speed range where the inlet valve 9 advances to the intake passage 4 while it is opened in a position opened in an intermediate speed range.