The item has no copyright markings on it as can be seen in the links above. At bottom is Litho in USA, 46105 and 54/269. These look to be associated with the printing of the poster.
Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (50 p.m.a.), Mainland China (50 p.m.a., not Hong Kong or Macao), Germany (70 p.m.a.), Mexico (100 p.m.a.), Switzerland (70 p.m.a.), and other countries with individual treaties.
{{Information |Description=Poster for the 1954 film ''Tobor the Great''. |Source=[http://media-cache-ec0.pinimg.com/originals/64/7c/1f/647c1fc8eb682e974ab698a4814f508c.jpg source] |Date=[http://www.imdb.com/title/tt0047590/ 1954] |Author=Republic Pictu...