PURPOSE: To prepare high-quality soybean milk, by deactivating an enzyme participating in soybean milk odor and an enzyme taking part in nutrition hindrance having different heat temperature and heat time of soybean raw material by heating in different places under proper conditions before it is sent to a hot-water grinder.

CONSTITUTION: In the storage tank 1 for hot water, etc., the cylinderical case 6 having the screw conveyor 5 in it, the hopper 8 at the top of the bottom part, and a great number of the through holes 7 at the periphery of the lower part is set slantingly, and the discharge outlet 9 for raw material soybean is set at the top part wherein the case 6 is protruded to the outside of the storage tank. The discharge outlet 9 is connected to the top end of the hopper 26, the top end of the hopper 26 is provided with the hot water feed pipe 32, the stirring blades 34 and the constant delivery screw 35 are set in the hopper 26. The cylindrical steam jacket 30 having the steam jet holes 27 on the inner periphery is laid at the outer peripheral part of the screw. The grinding chamber 13 having the ring-shaped steam jacket 24 on the periphery is set below the screw, and the grinding chamber is equipped with a pulverizer consisting of the fixed whetstone (a) and the rotary whetstone (b).