Abstract: An audio transmission system of the present invention includes: an unmanned aircraft; a steering terminal that is used to steer the unmanned aircraft; and an information terminal configured to access a server providing a service for translating text data created in an official language of a country into a designated language other than the official language, and converting the translated text data into audio data, the information terminal being able to download the audio data from the server. The information terminal transmits the audio data in the designated language downloaded from the server to the unmanned aircraft, and the unmanned aircraft outputs the audio data in the designated language as an audio message from a speaker attached to an airframe.