PURPOSE: To reduce a humming sound offensive to the ear during the low rotation of an engine regarding an intake-exhaust device for an internal combustion engine with each intake pipe and/or each exhaust pipe supported floatingly to the engine body using elastic tubes in order to reduce vibration and noise.

CONSTITUTION: An intake-exhaust device for an internal combustion engine is provided with elastic tubes 5a, 5b, 5c, 5d, 5e, 5f for supporting each intake pipe and/or each exhaust pipe, communicated with each cylinder, floatingly to an engine body. Among these elastic tubes, the elastic tube 5a or 5f of at least one of the cylinders positioned at both ends has a larger elastic constant compared to the elastic tubes of the cylinders positioned inside.