To prevent reflection of engine noise and the like entering from the foot side of an occupant at time lower part of a dashboard, into a cabin.

A plate-like under cover 23 is fixed in a horizontal state to the lower end of an open part 21b of an instrument panel 20A, and its tip is extended into a position near a dashboard 10. An outer sound absorbing layer 24 formed of porous material is stuck to the surface, facing a cabin R, of the under cover 23. An inner sound absorbing layer 25 is stuck to the surface, facing the inside of the instrument panel 20A, of the under cover 23. The tip of the sound absorbing layer 25 is pressed to the dashboard 10. Engine noise and the like entering from the foot side of an occupant at the lower part of the dashboard 10 can be absorbed by the outer sound absorbing layer 24. The return of noise into the cabin due to reflection at the under cover 23 can be effectively prevented so as to be able to keep the inside of the cabin silent.