This study is to measure and compare the hardness and tensile strength of each time after we recast seven times continually only with and metal alloy Chromium-Cobalt alloy used in the production of partial denture frame work. The result of the experiment were as follow; 1) The result of the hardness measurement The result of the first casting was $490.48{pm}38.38$ and that of the second recasting was $455.18{pm}35.61$ and form the third recasting. the result were $518.38{pm}37.68$ and over. The change of the hardness difference between each recasting was as follow; The hardness difference between the first casting and the second recasting was $35.25{pm}31.93$ and that between the second recasting and the third recasting was $63.20{pm}54.02$. There was a statistically significant difference(P<0.01) in the above hardness, however, there was little difference on the whole. And after the third recasting, the hardness grew high a little bit. That is why low-melting metals such as Cr, Mn, Cu of alloy ingredient was evaporated or there was an effect of changes in metal crystal structure, I suppose. 2) The result of the tensile strength measurement. There was a statistically significant difference(P<0.01) between the first casting and the second, the fourth recasting, however. there was little difference in general.