The trend towards point-of-care and the advance in mobile technologies bring the potential to employ Mobile Nursing Information Systems (MNIS) in nursing care routines. However, adopting the MNIS is not simply a case of purchasing the required hardware and software, but rather a social interaction process between users, organizations, and the environment. Therefore, this study developed a framework of twelve factors affecting the decision to adopt/not to adopt the MNIS in the nursing department, and tested it from the perspective of the nursing administrators. A mail survey was conducted to collect the opinions of 84 nursing administrators, and a discriminant analysis was used to identify the critical factors for the adoption/non-adoption of the MNIS. Business competition, external suppliers’ support, and internal needs were identified as being significantly associated with the adoption of MNIS. Potential adopters can apply the results of this study as a reference when making the adoption decision regarding MNIS, while non-adopters and vendors can examine the resistance to MNIS.