The phenomenon of population growth is a common problem in Indonesia. This will raise the emergence of a slum in urban areas, including Tanjungpinang City. The purpose of this study was to analyze factors affecting slum settlements in Tanjungpinang, Riau Islands. The method used was Geography Information Systems (GIS) with survey approach with instruments involving observation guidelines and interviews. The data analysis method employed the slum assessment scoring method from the Ministry of Public Works and Housing (MoPWH) Directorate General of Human Settlements. The results show that the factors rendering slum settlements in Tanjungpinang, Riau Islands can be classified into four aspects: irregularity buildings, unmet demand for daily needs water, wastewater management system that does not meet the technical standards and the lack of fire protection infrastructure. Based on these criteria, the slumness of Tanjungpinang was considered at a low level. The recommendation of this study was to repair and improve environmental conditions, in both physical and social terms.