Sealing device for the flap track for the flap-actuating shaft, in the belly fairing of an aircraft, with a top hollow body 1 and a bottom hollow body 7 which are flexibly compressible, each comprising at least one interior chamber 2, 8 with open sides 2a, 2b, a wall 3, 9 with respective external contact surfaces 3a which are in flexible contact with each other, the outer surfaces 4a, 10a of the front walls 4, 10 of the hollow bodies 1, 7 jointly forming an outer sealing surface 11 which covers the flap track 19, said hollow bodies 1,7 having jointly a vertical compression flexibility such that the contact surfaces 3a, 9a retract around the actuating shaft 20, the interior chambers 2, 8 extending between the front walls 4, 10 and rear walls 5, 11 of the hollow bodies 2, 7.