This research analyzes the conversational interruptions occurred in the first presidential debate of Donald Trump vs. Joe Biden in 2020. The purposes of this research are to explain the types and contextual causes of the conversational interruptions in the presidential debate. The approach employed in this research is the conversation analysis which focuses on analyzing the occurring data in real-life like the presidential debate. Other than that, the researcher also uses two different theories to analyze data. The first one is theory by Li to analyze the type of conversational interruption and the second one is theory by Wardhaugh to analyze the contextual cause of conversational interruption. The result of this research shows that there are two types of conversational interruption found in the debate which are successful interruption and unsuccessful interruption. The researcher also found that there are four contextual causes of the conversational interruption which are breaking up, seeking clarification, correcting, and rejecting. There are no cooperative conversational interruptions that occurred in the presidential debate because both participants of the debate were against each other and had no need to help the other in the debate.