Abstract: A knot retainer (1) for preventing a knot (2) comprising a knot body (8) from unintentionally becoming undone. The retainer comprises a plate-like member (3) and at least one thread-like member (4). The plate-like member (3) comprises a first end (5) and a second end (6) opposite the first end. The plate-like member further comprises first fastening means (10, 12, 13) for attaching and holding a first portion (16) of the thread-like member at or near the first end and second fastening means (11, 14, 15) for attaching and holding a second portion (17) of the thread-like member at or near the second end. The at least one thread-like member comprises at least a third portion (18) and a fourth portion (19) for being arranged adjacent the knot body on opposite sides thereof. At least one of the plate-like member and the thread-like member is elastic.