Recently, violent crimes against the socially disadvantaged have become more frequent and became serious social issues. In addition, compared to the past, the crime methods have become more diverse and intricate, which results in larger damages. For those reasons, the public are increasingly concerned about crimes and it is detrimental to the quality of life in general. Currently, safety in alleys and other residential spaces is protected only by mechanical and managerial functions such as CCTV and police patrol. Safe environment from crimes can be achieved only if there are environmental and spatial plans such as CPTED (Crime Prevention through Environmental Design) principles. The purpose of this study is to propose a direction for spatial planning that can prevent crimes through environmental elements, by researching the spatial planning and current status of alleys and residential spaces from the viewpoint of CPTED. To do so, first, a review checklist was created based on five principles of CPTED and field surveys were conducted on the northern districts of Busan with high crime rates. Second, the problems were analyzed through the field surveys and checklist was classified based on five principles of CPTED to propose improvements for each item. Also, a computer graphic simulation was used to suggest a design proposal. We expect that the application of the basic environmental design principles and guidelines for CPTED will have the effect of creating crime-free and safe spaces in alleys and residential environment.