PURPOSE: To provide a fixing structure of a foldable seat for a vehicle where the number of parts and the number of the assembling manhour are not in creased, and projection of a locking hook 30 of the foldable seat into the cabin can be prevented.

CONSTITUTION: In a fixing structure of a foldable seat for a vehicle, a hook cover part 33 capable of covering a locking hook 30 is provided can a tension belt to release the engagement of the locking hook 30 with a striker. A projecting part of the locking hook 30 projecting from the rear surface of a seat cushion can be covered by a hook cover part 33, and the projecting part of the locking hook 30 made of steel plate can be prevented from being projected into the cabin. The increase in the cost can also be suppressed to the minimum because no additional members are required to be provided.