The present invention provides a method of joining members to be joined by use of an Au—Sn brazing material, in which joining is performed by adjusting the composition and thickness of the Au—Sn brazing material so that the Sn content of the joint after joining is from 20.65 to 23.5 wt %. The invention has been completed on the basis of the discovery that the true eutectic point of this alloy system corresponds to 20.65 wt % Sn. In the invention, as means for adjusting the composition of a resulting joint, it is necessary to appropriately adjust the composition and thickness of a brazing material according to the thickness of a gold plating. In the invention, the relationship between the brazing material thickness and the gold plating thickness is shown when the brazing material to be used has an Sn content of 21 wt % to 25 wt %.