In order to analyze liquidity change according to increasing the charge of superplasticizer, we inputted charges by dividing into six steps, 0% through 1.25%; at the same time, to observe liquidity change according to the change of charge-time, we carried out the experiment applying 30-minute intervals, i.e. at beginning of mixing, 30, 60 and 90 minutes. The results are below. 1) According to increasing the charge of superplasticizer, the liquidity of concrete was enhanced, however, when inputted 1.25%, a little segregation was occurred, which allowed us to make a conclusion that concrete performance would be deteriorated due to this segregation. 2) When we inputted 1.25% of superplsticizer, steady liquidity features were shown regardless of the charge-time of concrete, which allowed us to make a conclusion that this input would be the best for liquidity performance considering only liquidity features. 3) After analyzing the dynamical features of liquid concrete, the result showed that there was not significant effect on revelation of compressive strength. We concluded form this result that there was no influence on the stripping-time of a mold form. 4) When we charge superplasticizer in concrete more than 1%, we, in advance, should clearly judge the concrete performance required during constructing in site, as it were, the compressive strength or liquidity etc.; furthermore, we had better decide a charge and input-time of superplasticizer to meet the required performance.