A solder reflow apparatus may include a reflow chamber receiving a heat transfer fluid. The heat transfer fluid transfers heat to a solder for mounting an electronic part on a substrate. A heater heats the heat transfer fluid in the reflow chamber. A rail is arranged in an upper region of the reflow chamber and extends along a horizontal direction. A stage module may be movably connected to the rail and supports the substrate. The controller controls a positioning of the stage module to move the substrate supported by the stage module to different heights in a vertical direction.