A seat attachment structure for a vehicle having a seat hinge attached at one end of a seat, a first seat hook attached at the other end of the seat, a second seat hook attached substantially at the center of the seat, and a main locking mechanism and a sub-locking mechanism connected by a second cable. When locking the main locking mechanism, the sub-locking mechanism may also be brought into the locked state in conjunction therewith, and thus the seat can be locked easily and reliably. In addition, by providing a seat hook for the main locking mechanism at the other end of the seat, the seat hook for the main locking mechanism may be positioned at the farthest point form the hinge attached at one end of the seat. Therefore, when locking the main locking mechanism by pressing the end of the seat above the main locking mechanism downward by hand, a downward pressing force required to be exerted on the seat for generating a moment about the hinge may be reduced.