To provide a joint that contributes to reduction in number of components and prevents liquid dripping.

A plug 10 includes a cylindrical plug body 11 in which a plug side liquid passage 11a and a plug side air passage 11b are formed inside and outside, respectively, and the ends of the passages 11a and 11b are open. A plug valve 12 is mounted in the plug side liquid passage 11a of the plug body 11 so as to freely move forward/backward in order to open/close the opening 11c of the plug side liquid passage 11a. A socket 20 includes an inside tube 21 having a socket side liquid passage 21a formed inside and also a through-hole 21b for communicating between inside and outside formed on a side surface of the end connected to the plug 10. The socket 20 also includes an outside tube 22 forming an air passage 22a between the inside tube 21 and the outside tube 22 itself. A socket side valve 23 is mounted between the inside tube 21 and the outside tube 22 so as to freely move forward/backward. The socket side valve 23 opens/closes the liquid passages 11a and 21a and the air passages 11b and 22a.