An apparatus for producing metal sheets from extruded profiles of small thickness or of hollow chamber plates of light metal, preferably of magnesium or magnesium alloys, comprises an extruder for producing an extruded profile which is open along a surface line. A separating device is provided for cutting the extruded profile to length corresponding to the length of the metal sheet to be produced, or the hollow chamber plate to be produced. A bending unit is used for deforming the extruded profile into a U-shaped profile. An expansion unit is provided for expanding the U-shaped profile into a flat metal sheet or a hollow chamber plate. A stacking unit is also provided. At least one expansion unit is arranged parallel to the extrusion line and thus the extrusion and expanding processes are decoupled from one another.