The paper analyzed the vulnerable places to sexual crimes in Seoul with consideration of increasing women s sexual safety issues, by implementing the database system for calculation of regional Sexual Crime Prevention Index through public big data. Based on the situational crime prevention theory, the research aims to meticulously estimate the sexual crime risks exposed to the area residents with adding the addresses of the sexual ex-convicts which have not been applied to the previous studies, with collecting the public data of police organization, sexual crime occurrences, addresses of the ex-convicts, CCTV, etc. on the regional base, and with calculating how much resource was allocated in each Legal Dong of Seoul for sexual crime prevention. As a result, the implemented database system presented rankings of Legal Dongs in terms of sexual crime prevention possibility by their index. For the government, findings of this system can provide information for additional prevention resource demands on the specific region in Seoul. For the individual users, this system can contribute to the residential site safety and selection by useful information for its sexual crime vulnerability.