A mounting method and a mounting device, the method comprising the steps of, after positioning connected matters relative to each other, moving a movable wall positioned therearound until coming into contact with one connected matter holding means to form a local chamber having a local closed space, closing both connected matters in the chamber, depressurizing the inside of the chamber, moving the connected matter holding means in a direction for reducing the volume of the chamber and moving the movable wall according to the movement, and connecting both connected matters to each other by pressing, whereby, since the connected part and its periphery can be locally and efficiently enclosed separably from surroundings, and the local chamber capable of properly varying the shape of the enclosed space can be formed interlockingly with the connecting operation while maintaining the enclosed state even at the time of connection, a specified mounting can be easily performed by a small device.