網際網路及智慧型手機的普及，使得青少年朋友習慣經營社群或加入社群，在社群媒體上漫遊、打發時間與經營人際關係，若遇到問題時大多選擇在網路上蒐集相關資訊。青少年時期正處於身與心快速發展的階段，在身心發展變化的同時，也渴望著有人能夠瞭解他們的內在世界，但高度的手機使用行為，減少了和朋友彼此分享的時間，會帶來壓力和沮喪，明顯影響其生理、心理健康以及社會互動關係，導致人際關係上得不到友誼，甚至學習也會受到影響，因此，本研究以桃園S國中一到三年級的學生為抽樣對象，採用問卷調查法來作為資料收集的方式，並使用獨立樣本t檢定、單因子變異數分析、卡方檢定、相關分析、雙因子變異數分析、迴歸分析等方法，探討青少年們在使用社群媒體時與人際關係、學業成就和從眾行為之間的關係。研究結果發現「使用動機」和「感知偏好」是影響學生使用社群媒體的主要因素。在「依附行為」的層面中發現越高年級學生情形越嚴重。當青少年接受某項議題時間愈長時，對於「內化行為」中的從眾行為表現越明顯。青少年每天使用手機時間超過2.1小時就會導致其學業成就下降，而且使用時間越長情況愈嚴重。對人際關係的研究發現，青少年同儕社交間話題討論度愈高，對順從輿論、反智現象以及內化行為也愈好；因此，青少年於整體社群媒體使用行為傾向愈高時，整體的從眾行為愈明顯。最後，本研究提出具體建議，以提供學校老師、家長及學者後續研究之參考。

The popularity of the internet and smartphones makes teenagers are used to running social media or joining communities. The purposes of teenagers using running social media are for consuming time and managing interpersonal relationships. Most of them choose to collect relevant information on the internet. While the body and mind are developing and changing, teenagers are also eager for someone to understand their inner world. However, the high degree of mobile phone usage reduces their time which share with friends. Obviously, the mobile phone usage affects teenagers’ physical, mental health, occupational function or social interaction, affect interpersonal relationship, peer friendship and learning. Therefore, this study tries to explore the relationship about teenagers’ social media using behavior, interpersonal relationships, academic achievement and conformity behavior. This result finds that "Using motivation" and "perceived preference" are the two main factors that affect students' to use social media. The higher grade students are more serious in the "dependency behavior" than the low grade students do. Teenagers have significant differences at the "internalized behavior", and boys’ score is higher than girls’. When teenagers accept a certain issue for a long time, the more obvious the herd behavior in "internalized behavior" is. Teenagers use mobile phones for more than 2.1 hours a day, which will lead to a decline in their academic achievement. The research on interpersonal relationships explore that the higher the degree of discussion among young peers on social topics, the better they are against public opinion, anti-intellectual phenomena, and internalized behaviors. Therefore, the higher the tendency for young people to use social media, the more Herd behavior becomes more obvious. Finally, this research puts forward recommendations to provide reference for school teachers, parents to counsel teenagers, and scholars to make follow-up research.