PROBLEM TO BE SOLVED: To easily obtain expanded soybean embryos including a lot of functional components such as isoflavone and saponin, having a moisture content of 1-5% (w/w), and a bulk density of 37-43 g/100 ml, and presenting a cream color, and when boiling, having no grassy smell, presenting an orange color, leaving no core, having soft palate feeling equal to boiled rice, and free from shape collapse.SOLUTION: Expanded soybean embryos are obtained by putting soybean embryos on the flow of superheated steam flowing at a high speed in a long and slender passage, pressure heating by the steam while letting flow in the passage at a high speed of an extent of preventing precipitation retention on a low wall surface of the passage for a time long enough to sufficiently heat, separating the pressure heated soybean embryos from the flow of the steam followed by collecting, and rapidly discharging the collected soybean embryos together with a little amount of steam around there into gas with a lower pressure than the pressure condition.
