This paper proposes a runoff model which is developed to deal and cope with some problems unsolved for the estimation method of effective rainfall series in the flood runoff analysis. The outline is as follows:
(1) The runoff model is a storage-based type one named an Applied LST-II. It modifies the LST-II model（the Long and Short Terms Runoff Model）proposed by Kadoya and Nagai.
(2) By introducing the functional structure of rainwater infiltration in the upper tank of LST-II model,the effective rainfall concerned in the surface runoff and／or prompt subsurface runoff is automatically in the Applied LST-II.
(3) A runoff cycle of base flow is divided in five stages. The first stage and second stage are related to rainless periods. The recharge to base flow occurs during other stages. The runoff heights of base flow for each stages are derived from the diffrential equations.
(4) A procedure of runoff analysis is described to direct and low water runoff components. The model has１６parameters. They are identified by modifying the SP method（Standardized Powell method）proposed by Kadoya and Nagai.
(5) It is shown that the Applied LST-II model is expected to apply as a practical use through application in the Hii River basin of 911.4km^2. And it is estimated to be applicable as the distributed runoff model to the runoff analysis reflecting the effect of a spatially distribution characteristics of storm rainfall in a watershed.