Abstract: The closure device (D) for closing a bottle (1) comprises an overmolded cap (2) and ferrule (4) made of two different materials and prevented from moving relative to each other by tamperproofing means (43). The device (D) further comprises fastener means (3, 5) for fastening onto the neck (11) of the bottle. A first element selected from the cap (2) and the ferrule (4) includes a peripheral tongue (43) that is placed substantially around the entire outer periphery of the device (D) and that forms the tamperproofing means. This tongue is connected to a body (41) of the first element via tearable means (45) and includes patterns (47) designed to co-operate, while the tongue is connected to the body of the first element, with complementary patterns (27) formed in the second element selected from the cap (2) and the ferrule (4).