A dental implant comprising: a fixture implantable in an alveolar bone to provide an artificial tooth root; and an abutment comprising elastic legs (122, 124) respectively comprising a top portion couplable to a prosthesis and a bottom portion elastically coupled to an axial hole of the fixture, wherein the elastic legs include an elastic fastening leg acting to couple the abutment to the fixture using elastic bending in an axial direction and restoring force and an elastic non-fastening support leg that does not directly participate in coupling of the abutment to the fixture, wherein a first fastening portion is provided on an inner surface of the axial hole of the fixture, the first fastening portion comprising a concave-convex portion, such as a fastening recess depressed outward, in a predetermined location on the inner surface of the axial hole, and a first corresponding fastening portion is provided on an outer circumferential surface of the elastic fastening leg to be complementarily coupled to the first fastening portion provided on the inner surface of the axial hole of the fixture, and has a fastening protrusion, characterized in that the first fastening portion is provided in a circumferential direction of the inner surface of the axial hole of the fixture so as not to provide an annular shape along the entire circumference, such that the abutment is coupled to the fixture at a predetermined angle when the abutment is pushed into the fixture and the first corresponding fastening portion of the abutment is releasable from the first fastening portion when the abutment is rotated in the circumferential direction by a predetermined level of torque or higher applied thereto, and wherein, in a position in which the abutment is fitted into the fixture by complementary fastening between the first fastening portion and the first corresponding fastening portion, at a predetermined level of torque or lower, a function of preventing the abutment from rotating with respect to the fixture is performed, and at a predetermined level of torque or higher, the elastic fastening leg of the abutment is elastically bent in an inner diameter direction, and the abutment rotates in the circumferential direction, allowing the fastening protrusion of the first corresponding fastening portion to be released from the fastening recess of the first fastening portion, so that the fixture and the abutment are decoupled from each other. a fixture implantable in an alveolar bone to provide an artificial tooth root; and an abutment comprising elastic legs (122, 124) respectively comprising a top portion couplable to a prosthesis and a bottom portion elastically coupled to an axial hole of the fixture, wherein the elastic legs include an elastic fastening leg acting to couple the abutment to the fixture using elastic bending in an axial direction and restoring force and an elastic non-fastening support leg that does not directly participate in coupling of the abutment to the fixture, wherein a first fastening portion is provided on an inner surface of the axial hole of the fixture, the first fastening portion comprising a concave-convex portion, such as a fastening recess depressed outward, in a predetermined location on the inner surface of the axial hole, and a first corresponding fastening portion is provided on an outer circumferential surface of the elastic fastening leg to be complementarily coupled to the first fastening portion provided on the inner surface of the axial hole of the fixture, and has a fastening protrusion, characterized in that the first fastening portion is provided in a circumferential direction of the inner surface of the axial hole of the fixture so as not to provide an annular shape along the entire circumference, such that the abutment is coupled to the fixture at a predetermined angle when the abutment is pushed into the fixture and the first corresponding fastening portion of the abutment is releasable from the first fastening portion when the abutment is rotated in the circumferential direction by a predetermined level of torque or higher applied thereto, and wherein, in a position in which the abutment is fitted into the fixture by complementary fastening between the first fastening portion and the first corresponding fastening portion, at a predetermined level of torque or lower, a function of preventing the abutment from rotating with respect to the fixture is performed, and at a predetermined level of torque or higher, the elastic fastening leg of the abutment is elastically bent in an inner diameter direction, and the abutment rotates in the circumferential direction, allowing the fastening protrusion of the first corresponding fastening portion to be released from the fastening recess of the first fastening portion, so that the fixture and the abutment are decoupled from each other.