To provide an electronic-component mounting method whereby the joining faultiness of the electrode pads of a board to rear-surface electrode type electronic components can be suppressed while avoiding the destructions and degradations of the electronic components which are caused by heating them in reflow processes.

In the electronic-component mounting method, there are performed a stacking process for stacking successively solder pastes and the electronic components 200 on the front surface of the mother board 1 having a laser-beam transmitting quality, and a joining process for joining to each other the mother board 1 and the electronic components 200 by such a laser beam L transmitted through the mother board 1 from its rear-surface side to its front-surface side as to fuse the solder particles contained in the solder pastes. With respect to the electronic-component mounting method, there is so used in the joining process the laser beam L transmitted through the step-index type optical fiber 102 of an intensity-distribution uniforming optical system for uniforming the intensity distribution present in the cross-sectional direction of the laser beam L as to fuse the solder pastes.