Enterprise Resource Planning (ERP) is a product that enables organizations achieving their competitive advantage. However, the failures of ERP implementation are still considered quite high. This research was conducted to formulate the framework of self-assessment of open source ERP implementation readiness, which focused on the ERP pre-implementation aspects. The proposed ERP implementation readiness assessment framework was developed using the Fuzzy-based ANP (Fuzzy ANP), where the examined readiness factors are grouped into three categories, namely project management, organizational, and change management readiness. In order to see the application of the framework, we conducted a case study on an SME engaged in software development. We did focus group discussion with Chief Technology Officer, Chief Strategy Officer and Project Manager. The results showed that the company is not ready to implement open source ERP. Although the company is strong in the human resources aspect, they are still weak in other aspects so that they need some strategies to improve their level of readiness before implementing open source ERP.