Workability and quality control tend to have opposed notion from each other in construction. In the case of Typical Process of wet mortar for finishing work of the building, plastering, masonry and Tile work use adding water method to correct fluidity. and recently, despite using dry mortar which produced in plant, dry mortar also use adding water method to correct Workability. Therefore, Assuming the condition of construction site, we measured fluidity and compressive strength to evaluate effect of adding water and initial wet condition on quality control according to elapsed time. As a result, we recommend that Adding water should be carried out within 30minutes and W/M 1%. Placement should be shut down within one hour to prevent degradation of quality. Finally, We could be found initial wet condition is very important to secure basic properties.