The present disclosure relates to a 3D printer for construction for print-molding various structures, in which a main pipe 30 for transferring a filament material 31 therein is installed inside a nozzle 10 for discharging a printing material, such as concrete or mortar, to enable co-printing of the filament material 31 with the printing material while embedded in the printing material. According to the present disclosure, in constructing a structure by a 3D printer for construction, a printing material embedded with the filament material 31 as reinforcing material may be printed, and as a result, the effects of reinforcing tensile strength of the printed object and inhibiting crack of the printed object may be obtained.