Objectives: Depression and suicide rates among the elderly in Korea are among the highest in the world. From a mental health perspective, cities are highly vulnerable due to disconnected social networks, lifestyles, and insufficient open spaces. This study was performed to empirically analyze the effect of walking practice on depression among the elderly living in Seoul. Methods: The data were obtained through a face-to-face interview survey of 500 senior citizens living in Seoul using the proportional allocation method for five districts. In order to overcome the limitation of reverse causality between walking and depressive variables, the study tried to analyze the effect of walking practice on depression using a two stage probit least squares methodology. Results: The instrument variable was selected as the variable ‘whether there is an open space available for walking’, and this variable met both instrument relevance and instrument exogeneity. After adjusting for demographic characteristics (sex, age, income level, education, spouse, the number of people living together, housing type) and health status (the number of chronic diseases), we found that the walking practice of urban elderly significantly affects the depression. Conclusions: In order to prevent depression in the elderly, a strategy to promote physical activity, one of the non-pharmaceutical approaches, is very important. Based on the fact that walking habit has a significant effect on mental health, it is necessary to increase the walking practice rate of the urban elderly. In particular, in order to create active spaces such as green spaces and open spaces, an urban planning approach is simultaneously required. In addition, it is essential to create active spaces such as green spaces and open spaces that are urban planning approaches.