An electronic component mounting method for mounting a electronic component on a board, in which an Au bump provided at an electronic component is joined to a joining terminal formed on a board by using solder made of Sn or solder containing Sn and the electronic component is adhered to the board by means of thermosetting resin thereby to mount the electronic component on the board. The applied thermosetting resin is flown toward the outside by the lower surface of the electronic component, then a part of the solder particles contained within the thermosetting resin are made in contact with the side surfaces of the Au bumps which are heated to the temperature higher than the melting point of the solder and also another part of the solder particles are molten in a state of being sandwiched between the Au bumps and the electrodes. Thus, the diffusion of Sn into the Au bumps from the outside is promoted and so the density of Sn within the Au bumps can be increased. Further, the diffusion of Sn into the Au bump from a solder joining portion can be suppressed and so the generation of Kirkendall voids can be suppressed.