There is no doubt that a rapid increase in the use of social networks has taken place in recent years. Individuals use social networking with various motivations. Some researchers have investigated the motivations behind social media use. This article identifies the most important goals and motives of Iranian users in using "Instagram". Instagram is a social networking service made for sharing personal photos and videos. The ethnographic research method is based on non-participatory observation and semi-structured interviews with thirty users of this social media. Thematic analysis was conducted and the results show that Iranian users use Instagram with numerous motivations. These motivations include some items such as self-expression, entertainment, getting information and news, keeping in touch with friends and finding old-time friends. However, getting to know the private life of friends and celebrities is one of their main motivations for using Instagram. Although they may have entered Instagram with different motivations at first, they are interested in knowing about the private lives of others and especially the ideas of political and artistic celebrities - even if they do not believe in the ideas and perspectives of these celebrities.