An electronic device comprising: a housing including: a front plate , a rear plate disposed opposite the front plate , and a lateral member surrounding a space between the front plate and the rear plate and including a conductive portion and a non-conductive portion ; and an antenna module disposed in the space and including: a printed circuit board having a first surface disposed to face the lateral member in the space, and a second surface disposed opposite the first surface , and at least one antenna element disposed on the first surface or near the first surface in the printed circuit board , and configured to form a beam pattern toward the lateral member , wherein the conductive portion includes, when viewed toward the first surface , a notch having a recessed shape in a direction from the rear plate to the front plate , wherein the non-conductive portion is disposed at least partially in the notch and faces the at least one antenna element, wherein the notch has a third surface facing the rear plate , characterised in that the conductive portion includes at least one protrusion extended from a part of the third surface toward the rear plate and spaced apart from the first surface in a direction that the first surface faces, wherein, when viewed toward the first surface , the at least one protrusion does not overlap the at least one antenna element, and wherein, when viewed toward the first surface , the at least one protrusion comprises a fourth surface , a fifth surface , and a sixth surface , the fourth surface facing the rear plate , and the fifth surface and the sixth surface connecting the fourth surface and the third surface and disposed opposite to each other. a housing including: a front plate , a rear plate disposed opposite the front plate , and a lateral member surrounding a space between the front plate and the rear plate and including a conductive portion and a non-conductive portion ; and a front plate , a rear plate disposed opposite the front plate , and a lateral member surrounding a space between the front plate and the rear plate and including a conductive portion and a non-conductive portion ; and an antenna module disposed in the space and including: a printed circuit board having a first surface disposed to face the lateral member in the space, and a second surface disposed opposite the first surface , and at least one antenna element disposed on the first surface or near the first surface in the printed circuit board , and configured to form a beam pattern toward the lateral member , a printed circuit board having a first surface disposed to face the lateral member in the space, and a second surface disposed opposite the first surface , and at least one antenna element disposed on the first surface or near the first surface in the printed circuit board , and configured to form a beam pattern toward the lateral member , wherein the conductive portion includes, when viewed toward the first surface , a notch having a recessed shape in a direction from the rear plate to the front plate , wherein the non-conductive portion is disposed at least partially in the notch and faces the at least one antenna element, wherein the notch has a third surface facing the rear plate , characterised in that the conductive portion includes at least one protrusion extended from a part of the third surface toward the rear plate and spaced apart from the first surface in a direction that the first surface faces, wherein, when viewed toward the first surface , the at least one protrusion does not overlap the at least one antenna element, and wherein, when viewed toward the first surface , the at least one protrusion comprises a fourth surface , a fifth surface , and a sixth surface , the fourth surface facing the rear plate , and the fifth surface and the sixth surface connecting the fourth surface and the third surface and disposed opposite to each other. <EOS>