An electronic device (100; 300; 400) comprising: a housing including a front plate (102; 320), a rear plate (111; 380) facing away from the front plate, and a side structure (118; 310) surrounding a space between the front plate (102; 320) and the rear plate (111; 380); a heat dissipation member connected to electronic components including a processor and/or a communication module in the housing, wherein the heat dissipation member is configured to diffuse heat generated by the electronic components; at least one antenna module disposed adjacent to the side structure (118; 310) or at least partially accommodated in the side structure (118; 310), the at least one antenna module being disposed to be inclined or perpendicular relative to the front plate (102; 320) or the rear plate (111; 380); and a fixing member (501a, 501b; 801a) coupled to and at least partially surrounding the at least one antenna module , wherein the fixing member (501a, 501b; 801a) includes: a first heat transfer portion (515; 715a; 815) at least partially surrounding a rear face of the at least one antenna module ; and a second heat transfer portion (517a, 517b, 517c; 617) disposed to be inclined or perpendicular relative to the first heat transfer portion (515; 715a; 815) while being in contact with the heat dissipation member , the second heat transfer portion (517a; 517b; 517c; 617) being configured to transfer heat from the first heat transfer portion (515; 715a; 815) to the heat dissipation member . a housing including a front plate (102; 320), a rear plate (111; 380) facing away from the front plate, and a side structure (118; 310) surrounding a space between the front plate (102; 320) and the rear plate (111; 380); a heat dissipation member connected to electronic components including a processor and/or a communication module in the housing, wherein the heat dissipation member is configured to diffuse heat generated by the electronic components; at least one antenna module disposed adjacent to the side structure (118; 310) or at least partially accommodated in the side structure (118; 310), the at least one antenna module being disposed to be inclined or perpendicular relative to the front plate (102; 320) or the rear plate (111; 380); and a fixing member (501a, 501b; 801a) coupled to and at least partially surrounding the at least one antenna module , wherein the fixing member (501a, 501b; 801a) includes: a first heat transfer portion (515; 715a; 815) at least partially surrounding a rear face of the at least one antenna module ; and a second heat transfer portion (517a, 517b, 517c; 617) disposed to be inclined or perpendicular relative to the first heat transfer portion (515; 715a; 815) while being in contact with the heat dissipation member , the second heat transfer portion (517a; 517b; 517c; 617) being configured to transfer heat from the first heat transfer portion (515; 715a; 815) to the heat dissipation member . a first heat transfer portion (515; 715a; 815) at least partially surrounding a rear face of the at least one antenna module ; and a second heat transfer portion (517a, 517b, 517c; 617) disposed to be inclined or perpendicular relative to the first heat transfer portion (515; 715a; 815) while being in contact with the heat dissipation member , the second heat transfer portion (517a; 517b; 517c; 617) being configured to transfer heat from the first heat transfer portion (515; 715a; 815) to the heat dissipation member . <EOS>