As a family name, Ju may be written with either of two hanja, one meaning "red" (朱; 붉을 주), and the other meaning "around" (周; 두루 주).
[1] The 2000 South Korean census found 215,010 people with this family name.
[2] In a study by the National Institute of the Korean Language based on 2007 application data for South Korean passports, it was found that 50.6% of people with this surname spelled it in Latin letters as Ju in their passports, and another 46.9% spelled it as Joo.
Rarer alternative spellings (the remaining 2.4%) included Chu and Choo.
[3] People with these family names include: There are 56 hanja with the reading "ju" on the South Korean government's official list of hanja which may be used in given names; they are listed in the table at right.