The aspect of visual accessibility to urban green spaces is an important factor because it contributes making pleasant environment by increasing the visual experience of nature in urban environment. But we have tried neither to consider nor to measure it. Since he concept of visual accessibility has not formally defined yet, it was operationally defined in this study. And then the model of measuring visual accessibility was suggested and verified through the case study on neighborhood parks in Seoul. The findings are as follows : 1) The concept of visual accessibility is defined as opportunity and potentiality to observe green spaces. 2) The model of measuring visual accessibility deals with not only adjacent area but also viewshed area. In adjacent area, considering factors are the area of road adjacent to green spaces and the area of exposed green spaces. In viewshed area, considering factors are the area of road located in viewshed area, the area of exposed green spaces, and the weight according to observing distance. 3) The final model of measuring visual accessibility suggested in this study is as follows.