Non-binding-mark sock

A non-binding-mark sock, comprising:

• a sock sole;
• and
• a straight sock leg connected to the sock sole, an upper portion of the straight sock leg being an opening end, an inner surface of the straight sock leg having at least one transverse annular convex portion near the opening end,
• the at least one transverse annular convex portion formed by an elastic zigzag thread, the at least one transverse annular convex portion forming a plurality of convex segments and a plurality of U-shaped ends on an inner surface of the at least one transverse annular convex portion along the elastic zigzag thread, and the convex segments protruding from the inner surface of the straight sock leg, wherein the elastic zigzag thread is stitched onto the inner surface of the straight sock leg along an annular orientation by sutures of additional threads to fix the U-shaped ends of the elastic zigzag thread on the inner surface of the straight sock leg and the elastic zigzag thread does not form stitches itself, so as to form the at least one transverse annular convex portion and the convex segments of the at least one transverse annular convex portion,
• wherein the convex segments of the at least one transverse annular convex portion are transversely located on the inner surface of the straight sock leg, each of the convex segments extends up and down, and the convex segments are arranged in parallel and formed by the elastic zigzag thread only.