This paper explores how social media affect sociology. In particular, it examines how social media are manifested in sociological research trends from 2009 to 2018. For this purpose, it analyzes 45,873 articles in 147 sociological journals written in English, based on text mining and topic modeling. This research finds: first, that social media have rapidly become a key research theme since it appeared around 2010 in sociology journals, and secondly that social media have changed the dynamics of social movement. These findings imply that social media, explosively expanded in their link with smartphones, affect everyday life and thereby have become a source for sociologists to find new data unavailable in the past, to observe and analyze social phenomena with those new data. This paper contributes to the understanding of how social media have changed the research landscape of world sociology, grounded in empirical data.