A bone plate system for fracture surgery is provided. The bone plate system includes a bone plate and a locking screw. The bone plate includes an upper surface, a lower surface facing a bone, and a locking hole in which an even-number-ridge internal thread is formed. The locking screw is coupled to the locking hole. The locking screw includes a head tapered so that a diameter thereof decreases along a center axis, a shank extending from the head, a double-ridge external thread formed on the head and configured to be tightened to the even-number-ridge internal thread, and an external thread formed on the shank and configured to be fastened to the bone.
