In the rapidly aging society of Taiwan, keeping interpersonal interaction with others becomes an increasingly important issue to elder adults. None or little social interaction with others causes psychological problems in elder adults’ general life. With the development of information communication technology (ICT), the use of social networking sites for interpersonal interaction thus has emerging importance. Nevertheless, elder adults’ may not be able to accept the use of such sites for social interaction for the late appearance of the technology in their life. This study is therefore motivated to explore elder adults’ use of Facebook for social interaction based on TAM2. Data of 120 valid respondents were gathered and analysed with PLS. The results showed that perceived use anxiety significantly decreased elder adults’ acceptance of social networking site for social interaction although friends’ use and family’s use motivated their usage. Furthermore, perceived social usefulness was not shown of significant impact on their usage. The results demonstrated the importance of others’ use and the reduction of use anxiety in elder adults’ acceptance of social networking sites as a way to reach others and to keep themselves socially relevant to others.