This research is motivated by the phenomenon of the lack of public purchasing decisions on Islamic insurance services. This can be seen from the low number of assets and market share of Islamic insurance services. The purpose of this research is to determine the reasons for purchasing decisions of insurance participants in making purchasing decisions on insurance services in Prudential Syariah, as a player in Islamic Insurance in Indonesia and which variable that become the most dominant factor. The research method used is explanatory survey with data collection technique employing questionnaire. Population in this research is participants of insurance services in Prudential Syariah with sample of 70 respondents using simple random sampling technique. Data analysis technique used is method analysis of CFA (Confirmatory Factor Analysis) by using Amos. The research findings show that the individual differences, environment and marketing mix variables have a positive and strong relationship in purchasing decisions Prudential Islamic insurance services and the most dominant variable is individual differences.