Abstract: Device (1) for loading and unloading containers (2) into an out of an enclosure of an installation (3) for treating substances contained in containers (2), the device including a support structure (17) and third means for moving second means (14) to a position higher than said containers, said second means (14) acting as a stop during loading and as a pusher during unloading, characterised in that said device includes an extendible platform (10), said extendible platform unfurling from said support structure (17) and in that said third means comprise parts (16a 16b) that unwind from said support structure (17) to the interior of the enclosure. It is completely automatic, fast, takes up little space and is easy to disassemble. FIGS. 8a, 8b.