A tonneau cover device includes a tonneau cover coupled to a hatchback door. A movable guide arranged on the tonneau cover is guided by a fixed guide arranged in the vehicle to guide the tonneau cover. The movable guide is separated from the fixed guide when the hatchback door opens. A controller moves the tonneau cover to an extension position when the hatchback door closes and a storage position when the hatchback door opens. A detector detects whether movement of the tonneau cover is obstructed due to contact with an object. The controller temporarily interrupts movement of the tonneau cover when the detector detects that the movement of the tonneau cover to the storage position has been obstructed and restarts the movement of the tonneau cover to the storage position when determining that the movable guide has been separated from the fixed guide as the hatchback door opens.