To certainly prevent contents from leaking when transferring the contents from a certain container to other container.

There is provided a joint member 20 for transferring the contents from a container having a mouth to other container having a mouth. The joint member 20 includes: a tube body 22 formed in a tubular shape and having both end portions which are formed such that the mouths of the two containers can be insertion-connected into them, respectively; and a tubular closely contacting portion 30 prepared in the tube body 22, capable of intervening between the two mouths of the containers respectively insertion-connected into both the end portions of the tube body 22, while being closely contacted to the front circumferential edges of the two mouths, respectively.