Illocutionary acts are a type of speech act that convey meaning beyond the literal meaning of the words. This study aimed to identify the types of illocutionary and the dominant type of illocutionary acts in J. K. Rowling's speech at Harvard University graduation in 2008. The method used in this study was qualitative descriptive by analyzing the script of the speech as the main data provided on the internet. The data was first collected by watching the video on YouTube and then finding the script of the speech on the provided website in the description box. The analysis of the speech identified 47 utterances that classified into four types of illocutionary acts, such as representative, expressive, directive, and commissive. The most dominant type was representative with 23 utterances in total (48.9%). Then, it followed with 12 (25.5%) of expressive, 7 (14.9%) of commissive, and 5 (10.6%) of directive.