A tube joint includes a joint body having a through hole to serve as a fluid passage provided along a direction of an axis, a nut member for connecting a tube to the joint body, and an insert bush inserted and fitted to an opening of the joint body and having an insert section to be inserted into the tube and an expanded section protruding from one end of the tube. The expanded section is formed with first projections which make linear contact with an inner wall surface of the opening and which function as seals.