Trunk box structure of automobile

A cargo compartment structure for an automobile comprising:

• a trunk box disposed in a cargo compartment in a rear part of the automobile, the trunk box having an opening on its upper side;
• a cargo board having an upper face and a lower face, the cargo board capable of changing its position between a closed position where the opening is covered by the cargo board, and an open position where the opening is opened, and where the upper face of the cargo board in the open position is waterproof, the open position of the cargo board being frontward of the closed position, and the cargo board being in the cargo compartment in the open position;
• and
• a board holder for holding the cargo board in a specific state so that the upper face of the cargo board is downwardly inclined toward a rear side of the automobile so that water flows from the cargo board and into the trunk box, and so that while the cargo board is in the open position, a rear end of the cargo board is disposed rearward of a front end of the trunk box;
• wherein the board holder is provided on a backside of a seat back of a seat that is disposed frontward of the cargo compartment, and
• wherein the board holder holds the cargo board in the specific state while the seat is in an unfolded state.