Forming method and forming system

A forming method of forming a piece between a surface of a mass of a molten material and a starter surface of a forming starter member by gradually separating said surface of said mass and said starter surface from each other, after said starter surface has been brought into contact with said surface of said mass, said forming method being characterized by:

• covering at least a portion of said surface of said mass which portion is wider than said starter surface, by a partition member having a plurality of partition walls which are spaced apart from each other by a spacing interval permitting said partition walls to divide a corresponding surface partially constituting said portion and corresponding to said starter surface, into a plurality of segmental surfaces, and then separating said partition member and said forming starter member from each other while keeping said partition member in a state for dividing said corresponding surface into said plurality of segmental surfaces, after said surface of said mass and said starter surface have been brought into contact with each other with said starter surface being held in contact with or proximity to said partition member.