While automation in public transport has gained new momentum in recent decades, the Autonomous Train (AT) is still in its infancy. To guide the deployment of the AT, it is necessary to study its acceptability by the public. The aim of this study was to investigate for the first time the factors that influence the acceptability of the AT. This qualitative study comprised interviews divided into 3 parts. The first part was devoted to free evocation of the AT, while the following ones asked participants to express themselves on the definition of the AT without a driver but with on-board staff (GoA3) and then without any staff on board (GoA4). Thirty participants were interviewed. The sample was balanced in age, gender, train usage, and living location. The semi-structured interviews were recorded, transcribed, and analysed according to the method of thematic content analysis. Overall, the results showed a lack of knowledge and an idealized representation of the AT. Participants expressed several concerns inherent in the deployment of ATs. Lastly, the intention to use was more favourable in GoA3 than in GoA4. In fact, the participants expressed rejection of GoA4, due to the absence of on-board staff and lack of trust in remote communication tools and train supervisors. This article is the first to explore the public acceptability of the AT by adopting an interview methodology to avoid priming participants' responses. It thus adds to the field of research on the acceptability of autonomous vehicles the railway world which previously focused on driverless subway and freight trains only and now opens the idea of AT on a regular train service.