Every enterprise expects successful adoption of Information Technology (IT) to support their business process. While there has been many research conducted to establish the factors that lead to the successful adoption of IT in an enterprise, this research underlines the importance of accommodating external factors specific to the enterprise with regard to the acceptance of an Enterprise Resource Planning (ERP) software. A case study in a manufacturing company which utilizes ERP software to support their business process is presented to identify factors that drive its adoption. During the conceptualization of the IT adoption model, we found that external factors that drive the adoption resemble the model of Decomposed Theory of Planned Behavior (DTPB). These factors are mapped into three main variables in the model: attitude, subjective norm, and perceived behavioral control that affect the intention of users to use the software. The Structural Equation Modeling and multiple regression method were employed to analyze the relation between factors within the model, and to identify which variables contribute to the acceptance of the software. From the study we found that user’s attitude toward the software significantly influence the intention to use the software (path coefficient = 0.9964) while it is interesting to see that subjective norms and perceive behavioral controls is not significant to the user’s intention (path coefficient= -0.0225 and path coefficient= -0.0417, respectively). This concludes that the intention to use the ERP software in the enterprise is largely determined by positive attitudes toward the software, including understanding the benefits from its adoption.