Abstract: A connector (1) is constituted by a first member (10) and a second member (40). The first member (10) has a male connecting portion (11) at a first end and a screwing structure (26) at a second end. The male connecting portion (11) is inserted into a female connecting portion (41) of the second member (40). A first engagement structure (15) is provided on the first member (10), and a second engagement structure (45) is provided on the second member (40) so as to be able to abut against the first engagement structure (15) in the circumferential direction. When a rotational force of a predetermined value or greater is applied to the first member (10) in a tightening direction (R1) of the screwing structure (26), one of the first engagement structure (15) and the second engagement structure (45) is plastically deformed by the other, so that the first member (10) is then rotatable in both forward and reverse directions relative to the second member (40).