There are many factors which affect the level of self-directed learning readiness. This study aims to investigate the relationship between external factors, internal factors and self-directed learning readiness. This study was carried out by using a census method for fourth year students of medical program of Tadulako University. Data were analyzed quantitatively using analysis tool of Structural Equation Modeling (SEM) with Partial Least Square (PLS) approach. Latent variables in this study consist of internal factors, external factors and self-directed learning readiness. The results of this study showed that as much as 24% of the variation in internal factors and 55.8% of the variation in self-directed learning readiness is could be explained by variations in the model. The external factors affected significantly on internal factors and self-directed learning readiness. The external factors have a direct positive affect to internal factors, while the external factors have indirect effect on self-directed learning readiness through internal factors mediation variable.