Locking fastening element (2, 2A, 2B, 2C, 2D) comprising: a base member (4, 4A, 4B, 4C, 4D); and a contact fastening element (6) comprising a base (8) and a plurality of engagement members (10) formed on the base (8), wherein: the base member (4, 4A, 4B, 4C, 4D) is integrally cast with the base (8) using a plastic material (5, 5a, 5b, 5c, 5d); the base member (4, 4A, 4B, 4C, 4D) has a surface formed with a plurality of openings (38-41, 38A-39A, 38B-43B, 38C-41C, 38D-41D) and at least one connecting groove (62-65, 62A, 62B-68B, 62C-64C); the base member (4, 4A, 4B, 4C, 4D) with a space (32) is shaped, which is designed to be filled with the plastic material (5, 5a, 5b, 5c, 5d) at the time of pouring, wherein the space (32) has the plurality of openings (38-41, 38A-39A, 38B-43B, 38C-41C, 38D-41D);and the plurality of openings (38-41, 38A-39A, 38B-43B, 38C-41C, 38D-41D) has a pair of openings which are connected to each other by the at least one connecting groove (62-65, 62A, 62B-68B, 62C-64C).