A tonneau cover device includes a tonneau cover attached to a hatchback door. A movable guide is arranged on the tonneau cover and is guided by a fixed guide, which is arranged in a vehicle. The tonneau cover moves 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. A controller moves the tonneau cover to where the movable guide can come into contact with the fixed guide in a state in which the hatchback door is open when the detector detects that the movement of the tonneau cover to the storage position has been obstructed.