Disclosed herein an artificial intelligence apparatus for recognizing speech with multiple languages including a microphone, and a processor configured to obtain, via the microphone, speech data including speech of a user with multiple languages, calculate a word recognition reliability of each word in the obtained speech data using an acoustic model of a main language, calculate a word recognition reliability of each word in the obtained speech data using an acoustic model of at least one sub language, select a language having a highest word recognition reliability for each word, convert the speech data into text in consideration of a word recognition result corresponding to the selected language for each word, and generate a speech recognition result corresponding to the speech data using the converted text.