The toxicity values heavy metals were evaluated by immobilization and chronic reproduction impairment tests, using Daphnia magna. Acute tests were evaluated by the inhibition of their mobilization after 24hrs without food addition. The tests of reproductive impairment were investigated for 21 days by food addition and exchange or water. The effect of each concentration was assessed by Probit analysis and t-test. The results obtained from this study were as follows : 1) The change of pH and DO was not significant in the acute tests, while, in the reproductive tests, pH was increased by 0.3~1.4 and DO also increased. 2) The $E_iC_{50}$ values of immobilization to Daphnia magna in artificial fresh water were $0.030mg/{ell}(Cu),;0.054mg/{ell}(Cd),;0.12mg/{ell};(Cr),;0.74mg/{ell}(Pb),;3.4mg/ {ell}(As)$ and the $NOE_iC$ values were $0.010mg/{ell}(Cu),;0.018mg/{ell}(Cd),;0.010mg/{ell}(Cr),;0.10mg/{ell}(Pb),;and;$1.8mg/{ell}(As)$. 3) The $E_rC_{50}$ values of reproductive impairment to Daphnia magna were $13.8mu extrm{g}/{ell}(Cu),;2.9mu extrm{g}/{ell}(Cd),;15.5mu extrm{g}/{ell}(Cr),;61.7mu extrm{g}/{ell}(Pb),;759mu extrm{g}/{ell}(As)$, and $NOE_rC$ values were $0.95mu extrm{g}/{ell}(Cu),;$0.54mu extrm{g}/{ell}(Cd),;1.2mu extrm{g}/{ell}(Cd),;$7.4mu extrm{g}/{ell}(Pb),;110mu extrm{g}/{ell}(As)$</TEX>. The results of tests using OECD artificial culture water were more sensitive than natural water for culturing. The presented data show that an artificial culture water is suitable in the experiment of bioassay for assessing the toxicity of marterials.