The research is based on Technology Acceptance Model (TAM) and combined with three main external variables:「Network Externality」、「Interactivity and Flexibility」、「Convenience」and 「Perceived Risk」to explore the behavior of using smartphone for elementary school teachers. The empirical results show that (1) gender、age and the attitude toward smartphone are the reasons that affect the usage rate of smartphone; (2) Technology Acceptance Model can be applied to the behavior of using smartphone for elementary school teachers; (3) External variables positively affected 「Perceived Usefulness」、「Perceived Ease of Use」and 「Intention of Use」;(4)「Financial Risk」and 「Social Risk」of 「Perceived Risk」negatively affected 「Intention of Use」. Therefore, if the authorities plan to increase the usage rate of smartphone for elementary school teachers, they can decrease the cost of usage and develop the application software that is suitable for elementary school teachers.