An automatic soldering method carried out using an automatic soldering device that includes a laser soldering device (1, 60, 70) and a Z-axis drive device driving the laser soldering device (1, 60, 70) in an up-down direction, wherein the laser soldering device (1, 60, 70) comprises: a body having a lower opening, an image capturing hole in communication with the lower opening, and an irradiation hole in communication with the lower opening; a mirror guiding the laser light to the lower opening by reflecting the laser light or allowing the laser light to pass therethrough, and guiding light having entered the lower opening by reflecting the light or allowing the light to pass therethrough; an image capturing device capturing an image of a workpiece through the image capturing hole and the mirror; a laser device constituted by a single laser light source; and an optical fiber guiding laser light from the laser device to enter the irradiation hole, and wherein the automatic soldering method comprises: forming a solder droplet on an electrode land, wherein the electrode land corresponds to the the soldering region; a first height adjustment step of adjusting, by the Z-axis drive device, a height of the laser soldering device (1, 60, 70) to a position at which the laser light has a preset irradiation diameter larger than a diameter of a solder droplet when viewed from above; a preliminary heating step of sending an irradiation command to the laser device, and irradiating the solder droplet with the laser light to heat the solder droplet to a temperature at which a flux solvent component volatilizes and a solder powder does not melt; a second height adjustment step of adjusting, by the Z-axis drive device, the height of the laser soldering device (1, 60, 70) to a position at which the laser light has a preset irradiation diameter smaller than the diameter of the solder droplet when viewed from above; and a main heating step of sending an irradiation command to the laser device, the irradiation command causing the laser device to emit the laser light with a higher output than in the preliminary heating step, irradiating the solder droplet with the laser light to heat the solder droplet to a temperature at which the solder powder melts, and performing soldering. a body having a lower opening, an image capturing hole in communication with the lower opening, and an irradiation hole in communication with the lower opening; a mirror guiding the laser light to the lower opening by reflecting the laser light or allowing the laser light to pass therethrough, and guiding light having entered the lower opening by reflecting the light or allowing the light to pass therethrough; an image capturing device capturing an image of a workpiece through the image capturing hole and the mirror; a laser device constituted by a single laser light source; and an optical fiber guiding laser light from the laser device to enter the irradiation hole, and wherein the automatic soldering method comprises: forming a solder droplet on an electrode land, wherein the electrode land corresponds to the the soldering region; a first height adjustment step of adjusting, by the Z-axis drive device, a height of the laser soldering device (1, 60, 70) to a position at which the laser light has a preset irradiation diameter larger than a diameter of a solder droplet when viewed from above; a preliminary heating step of sending an irradiation command to the laser device, and irradiating the solder droplet with the laser light to heat the solder droplet to a temperature at which a flux solvent component volatilizes and a solder powder does not melt; a second height adjustment step of adjusting, by the Z-axis drive device, the height of the laser soldering device (1, 60, 70) to a position at which the laser light has a preset irradiation diameter smaller than the diameter of the solder droplet when viewed from above; and a main heating step of sending an irradiation command to the laser device, the irradiation command causing the laser device to emit the laser light with a higher output than in the preliminary heating step, irradiating the solder droplet with the laser light to heat the solder droplet to a temperature at which the solder powder melts, and performing soldering. forming a solder droplet on an electrode land, wherein the electrode land corresponds to the the soldering region; a first height adjustment step of adjusting, by the Z-axis drive device, a height of the laser soldering device (1, 60, 70) to a position at which the laser light has a preset irradiation diameter larger than a diameter of a solder droplet when viewed from above; a preliminary heating step of sending an irradiation command to the laser device, and irradiating the solder droplet with the laser light to heat the solder droplet to a temperature at which a flux solvent component volatilizes and a solder powder does not melt; a second height adjustment step of adjusting, by the Z-axis drive device, the height of the laser soldering device (1, 60, 70) to a position at which the laser light has a preset irradiation diameter smaller than the diameter of the solder droplet when viewed from above; and a main heating step of sending an irradiation command to the laser device, the irradiation command causing the laser device to emit the laser light with a higher output than in the preliminary heating step, irradiating the solder droplet with the laser light to heat the solder droplet to a temperature at which the solder powder melts, and performing soldering.