Controllability of an input amount of a filler is improved to manufacture a molded substance having higher performance. The molded substance is manufactured by using an injection molding machine including: a cylinder 11 having a supply port 13h which is located upstream and through which a resin pellet RP is supplied and a supply port 15h which is located downstream of the supply port 13h and through which a filler F is supplied; a screw S disposed inside the cylinder; and a cutting machine 15. The cutting machine 15 continuously cuts a thread-state fiber (roving R) to a constant length, and inputs cut fiber pieces (filler F) into the supply port 15h.