A HYPE (HYdrological Prediction for the Environment) model considering impervious land cover in an urbanized watershed is set up to improve prediction precision of storm runoff. The set-up of the model is based on the Urban Atlas that is polygonal land cover data with impervious information. Firstly accurate impervious area ratios in a target watershed are calculated using the Urban Atlas, and the ratios are set to the HYPE model. Secondly, appropriate parameters to describe hydrological property in an urbanized area are implemented for the HYPE model. The model was applied for the watershed including urbanized area of Svedala, Sweden. It was demonstrated that impervious information obtained by polygonal impervious area ratio data contributed precision improvement of runoff prediction by HYPE model in urbanized area.