Abstract: The structural node of tight separable joint of bottle neck with its threaded screwed cap made of plastic includes a cylindrical neck (1) of bottle (2) and a screw cap (3) screwed onto outer thread (4) of the neck, the cap being provided with an inner thread (5) and an inner sleeve (8) joined inseparably with bottom (6) of the cap, whereas outer surface of the sleeve has at least one annular sealing tongue (11 or 13) end of which fits tight to cylindrical surface (12) of the neck (1) or end of the at least one annular tongue (11 or 13) is set tightly in eat least one circumferential groove (14 or 15) provided on inner cylindrical surface (12) of the neck (1). Moreover the cap (3), on inner surface of its sleeve portion (10), has annular offsets (17) situated above its thread (5) ends of which are tightly set in circumferential grooves (18) provided on outer surface of the neck (1) above its outer thread (4) and opposite said offset ends.