Influence of various inorganic builders on the fluorescent brightening effect of FBAs in built detergents were investigated. Experiments were mainly focused on : (1) the effect of each builder on the exhaustion ratio of FBAs and the maximum reflectance of washed clothes, the total effects of model built detergent. The results obtained were as follows : 1) The effects of each builder. The effect of water hardness for zeolite is very remarkable. As the concentration of zeolite increases, the exhaustion ratio of FBA decreases markedly. On the other hand, the effects of sodium tripolyphosphate and sodium sulfate increase with the increasing of concentration when used 0° DH water or low hardness water. The effect of sodium carbonate is not so remarkable because of the concentration of Na₂CO₃ is very low. The influence on the maximum reflectance (whitening effect) of each builder is not so remarkable with compared to the difference of the exhaustion ratio. 2) When the all sorts of builders were formulated in a model built detergent, the characteristics of each builder appears to put together, and higher whitening effect were obtained as overall results.