These days, RRI Samarinda not only has Indonesian programs but also foreign programs. The announcers use English to share information and also greet and communicate with listeners. Unfortunately, there are still many announcers who cannot use English properly and correctly and cannot avoid making errors when broadcasting. These errors can result misinformation or misunderstanding among the listeners. With that reason, this study was focused on the grammatical errors made by announcers on English Talk's program in Radio Republik Indonesia (RRI) Samarinda. This study was aimed to find out the types of grammatical errors and the sources of errors made by the announcers of English Talk’s program in Radio Republik Indonesia (RRI) Samarinda. The design of this study was qualitative research. The data of this study were the announcers’
conversations of English Talk’s program and there were 5 announcers as the sources of data. To collect the data, the writer used documentation, transcription of the data, and interview. The data were analyzed by using thematic analysis which included 4 steps starting from familiarizing and transcribing the data to making conclusions. The findings showed that there are 7 types of grammatical errors made by the announcers. Pluralization errors are the most frequent type among all the types of grammatical errors, followed by verb tenses errors, preposition errors, article errors, pronoun errors, question errors, and the last is word form errors. It was also found that the sources of errors are interlingual error, intralingual error, the learning context, slip of the tongue, and anxiety.