Abstract: The invention relates to a trench wall cutting device, to a trench cutter having a trench wall cutting device according to the invention, and to a method for cutting a cut trench using a trench cutter, which is constructed from at least two cutter modules, and at least one supply unit, which is connected to the cutter modules by means of cables. The first cutter module can be lowered into a guide trench before the second cutter module is placed onto the first cutter module. As a result, a cut trench can be created at a location with a restricted height, wherein in the trench the cutter has a guide height that is greater than the height of the site out of which the cut trench is generated.