PURPOSE: To improve the sealing performance by forming a shelf section on a portion of a chassis panel corresponding with the circumferential section of a trunk lid opening provided further outside than a weather strip provided at the edge of a trunk room opening and providing a seal member at the shelf section.

CONSTITUTION: In a seal structure where the edge section 5 will contact tightly with a weather strip 4 provided at the open edge 3 of a trunk room 2 when a trunk lid is closed thus to seal the open edge 3, the circumferential section X of the trunk lid 1 ahead of the weather strip 4 is stepped to form shelf sections 20, 21 on a west panel 8 and a rear fender panel 6 forming said open edge 3. Then seal members 22 contacting tightly with the edge 51 upon closing of the trunk lid 1 are provided on said shelves 20, 21. Consequently double structure is provided between each panels 6, 8 and the trunk lid 1 resulting in the improvement of the sealing performance.