This paper aims to investigate the effective application method to flood runoff analysis by the runoff model of storage type. As a runoff model of storage type, we deal with LTS-II model(Long and short terms runoff model) proposed by M. KADOYA and A. NAGAI. The model is composed of three tanks and has 14 parameters. As a result of analyzing the flood runoff data by the model, it is pointed out that the caluculated peak discharge is apt to simulate slightly small and the time of caluculated peak discharge occurs eariier than observed one. For dissolution of the problems, we propose a new procedure of runoff analysis, in which rainfall sequence is transformed by the delayed function. The function is evaluated from the distribution characteristics of slope length in a basin model and the equation of lag time applied the practical formula for the concentration time. By a flood runoff analys is using the delayed rainfall sequence as input rainfall data to LST-II model, it is showed that the problems on a peak discharge and the occurence time of it are improved.