Comparison tests were carried out on nine kinds of water reducing admixtures for concrete in market. The tests were made according to the JSCE Tentative Specification for Water Reducing Admixtures for Concrete 1966 on unit water content, bleeding, time of setting, compressive and flexural strengths, and drying shrinkage of concretes. Based on the results, the effects of the admixtures upon the concrete properties were discussed and the applicability of the above specification newly adopted was evaluated.