A survey study was conducted to investigate what kinds of social media are used as information sources and why. It also examined what kinds of actions users take in order to evaluate the trustworthiness of information provided by social media sources. A total of 446 undergraduate students from a public university participated in the study. A Web- based survey questionnaire consisting of two parts was used in the study: one part on the use and evaluation of social media sources and the other on the user characteristics. The study found that Wikipedia, social networking sites (e.g., Facebook) and online user reviews were among those frequently used for finding information, and that Wikipedia, YouTube, Q&A sites were used in both everyday-life and academic/course-related information seeking contexts. The study also revealed that strategies for evaluating the trustworthiness of information vary depending on sources (e.g., for Wikipedia, often check the quality/quantity of references/links provided; for YouTube and Q&A sites, check others' reactions). Based on the findings, suggestions were made for information literacy education.