In a device for manufacturing a filament three-dimensional bonded member includes: a molten filament supply device which supplies a plurality of molten filaments; a three-dimensional structure formation device which receives and then cools and solidifies the molten filaments so as to form a filament three-dimensional bonded member; and a controller which controls the molten filament supply device and the three-dimensional structure formation device, a hardness index measurement device is provided which measures the hardness index of the filament three-dimensional bonded member that is brought into a cooled state by the three-dimensional structure formation device, and the controller uses the information of the measurement of the hardness index measurement device that is fed back and thereby performs feedback control on at least one of the molten filament supply device and the three-dimensional structure formation device so as to reduce a variation in the hardness of the formed filament three-dimensional bonded member.