A surgical device for osteotomy allows for accurate determination of the angle at which a bone in the human or animal body should be corrected, and for precisely maintaining the angle constant during the entire surgical procedure. The surgical device having on its distal end a circular segment fixed to a distal end of a first blade and further moveably connected to a distal end of a second blade. The distal end of the second blade is allowed to move along the circular segment, wherein the proximal ends of the first and second blade converge at an angle. At least a pair of pin guide openings are provided in parallel for inserting and positioning at least two parallel pins or drill bits. The surgical device provides unique fixed reference means allowing to perform a precise surgery according to predetermined parameters and angles even at the final stages of the operation.