Online shopping is recently showing rapid development. There are a lot of e-commerce sites with several categories that appear in the community, along with changes in the way people shop from conventional shopping into virtual shopping. The most publicly visited e-commerce sites are C2C e-commerce sites, namely Tokopedia, Shopee, Bukalapak, and Elevenia. However, the popularity of C2C e-commerce sites must be reviewed since there is a decrease in marketing performance and in brand share over the period 2018-2019, which can weaken and harm C2C e-commerce sites. This research was conducted to analyze the factors that influence trust, purchase intention, and transaction security to improve consumer purchasing decisions of C2C e-commerce sites in Central Java. Using data from 160 respondents who had made purchases on the C2C e-commerce site throughout 2019, ten hypotheses were proposed through the Structural Equation Model (SEM) analysis. The results show that purchasing decisions were influenced by trust. Consumer trust increases if the quality of the products provided by the website is adequate, thus will shape consumer trust.