PROBLEM TO BE SOLVED: To provide a manufacturing method of seed paste having fine and uniform particle diameter by one-time continuous grinding treatment.SOLUTION: Discs 40 and 42 having grinding parts 40a and 42a with irregularities in fine groove shape are disposed opposite each other in vertical direction. Seeds are continuously ground between both of the grinding parts 40a and 42a which are relatively rotated with each other, so that seed paste is produced. Both of the discs 40 and 42 are made of ductile cast iron. The clearance X between the discs preferably satisfies the following expression: 0
