Aluminum plates of the same materials as the foam were attached by the casting process inserting the foam as a core to investigate the tensile property of open cell foams. Tensile properties of the open cell 6063 aluminum alloy foam of $10{sim}30$ PPI were measured before and after heat treatment. Densities of test specimens were between 0.14 and $0.29g/cm^3$. Tensile strength of the 6063 aluminum foam after heat treatment showed little change. C values were in the range of $0.41{sim}0.87$ for as cast foams and $0.11{sim}0.27$ for T6 heat treated foams in the eq. of ${sigma}^* _{pl}/{sigma}_{ys}=C({ ho}/{ ho}_s)^{1.5}$, and increased with increase in the cell size.