The present invention provides a fixture for a dental implant that serves as a replacement for a missing tooth and is implanted in the maxillary or mandibular bone. In this fixture invention the R/S border (the border between the rough and smooth surfaces) is formed to be inclined to a plane perpendicular to the long axis (central axis) of the dental implant fixture. The dental implant fixture prevents a marked decrease in the support for the dental implant due to bone reduction procedure in a patient having inclined bone crest, eliminates disadvantages in the aspects of expenses caused by the application of guided bone regeneration technique and also removes inconvenience of long operation time and possible infection, and also has a remarkable advantage of making convenient one-staged surgery possible in many cases.