PURPOSE: To improve an air charge efficiency by blowing air from an air cleaner into a first chamber provided with an intake preheating passage and a second chamber not provided with the intake preheating passage.

CONSTITUTION: In a three-cylinder internal combustion chamber, an intake device 1 is provided with a first chamber 2 arranged at a position far from an internal combustion engine A and a second chamber 3 arranged at position nearer than the engine A. Throttle bodies 4, 5 are mounted on one end of chambers 2, 3. An intake introduction passage 7 from an air cleaner 6 is connected to both the throttle bodies 4, 5 while being devided into two. At the first chamber 2, there is integrally provided an intake preheating passage 10 at which cooling water in the engine A is discharged from an outlet 10b after it is charged from an inlet 10a. Inside intake pipelines 15-17, 10-20 between the chambers 2, 3 and cylinders, changeover valves 21-23 which switchably operated by a control circuit 24 in relation to a temperature and the number of revolutions of an engine are arranged.