The purpose of this study was to investigate the comparison of physical properties of nonprecious metal alloys colored goldish yellow. The experimental groups were copper based dental alloy and control group was Ni-Cr based dental alloy used crown and bridges frameworks. Hardness was tested by vickers hardness tester, tensile strength was tested by universal tension tester. After testing the tensile strength of castings, the microstrucure and the pattern of fracture were investigated by scanning electron microscope and metallurgical microscope. The results were as follows : Hardness of Ni based alloy was higher than Cu based alloys. Hardness number of A group was 200.41$pm$16.10 Hv, B group was 194.33$pm$1.69 Hv, C group was 139.29$pm$2.19 Hv and D group was 293.81$pm$27.17 Hv, respectively. Tensile strength of D group was 56.42$pm$6.17 $kg/m^2$, A group was 50.39$pm$5.68 $kg/m^2$, C group was 45.13$pm$4.53 $kg/m^2$, B group was 45.25$pm$9.25 $kg/m^2$, in order, and D group was maximum tensile strength. The fractured surfaces of tensile specimens in the all groups showed the tendency to form large voids in the center of specimens. Thus the ductile fracture was changed into the brittle fracture with the fine grain size.