PURPOSE: To improve noise absorbing ability of a partition wall and to prevent invasion of water and dust to the interior of the partition wall.

CONSTITUTION: A dash panel 16 serving as a partition wall is arranged at a boundary part between an engine room 12 at the front part of an automobile body and the inside 14 of a car room. The engine room 12 side of the dash panel 16 is composed of an outer panel 18 formed of an aluminum sheet serving as an outer panel member. The inside 14 side of the car room of the dash panel 16 is composed of an inner panel 20 formed of an aluminum sheet serving as an inner panel member. Small holes 22 are formed in the inner panel 20 and the inner panel 20 forms a porous plate of aluminum. Foamed aluminum 24 serving as a foamed material is inserted between the outer and inner panels 18 and 20.