A method and a device for producing mirror units for heliostats, comprising a main body as a carrier of a reflective surface and a fixing carriage to ensure stress-free mounting of the main body during production, comprising the following features: a) a feed for main bodies (13) by means of a mirror-carrier delivery feed (3), b) a feed for fixing carriages (2) by means of running rails (4), c) a device for transferring a main body (13) into a fixing carriage, d) a mirror feed (8), e) an adhesive bonding device (5), f) a device for pressing a main body (13) together with a plurality of mirrors (11) and g) a measuring device (9) for checking relevant tolerances of the production process.