A rotary trench excavator comprises a propulsion unit (1) hingedly connected to a movable boom (2) carrying the working organ which consists of a system of rotors (9-11). Each rotor (9-11) is provided inside it, to ensure its rotation, with a supporting frame (6) having supporting (7) and guiding (8) rollers and a driving mechanism. To enable turning through 180 DEG of each of the rotors (9-11) individually or the system of rotors as a whole in the position of forward or reverse excavation, an additional frame (4) is connected to boom (2) of the excavator and to each of the rotors (9-11) by means of dismountable fixing units (13-26).
