Provided is a device in which the metal content existing in a joining interface is controlled. A manufacturing method for the device comprises: a step in which the surfaces of a first substrate and a second substrate are activated using a FAB gun; a step in which a plurality of metals are discharged by using the FAB gun to sputter a discharged metal body comprising the plurality of metals, and the plurality of metals are affixed to the surfaces of the first substrate and the second substrate; a step in which the first substrate and the second substrate are joined at room temperature; and a step in which heating is performed at a temperature that is high in comparison to the agglomeration start temperature of the plurality of metals and of the elements that constitute the first substrate or the second substrate. With regards to the step in which the plurality of metals are affixed, the density of the plurality of metals existing on the joining interface of the first substrate and the second substrate is set to 1×1012/cm2 or less by adjusting the exposure area of the discharged metal body.