An electronic device comprising: a housing including a first cover disposed to face a first direction, a second cover disposed to face a second direction opposite to the first direction, and a side member enclosing at least part of a space between the first and second covers; a slider to be inserted or withdrawn by being disposed to at least part of an area of the first cover of the housing; a flexible display disposed in the slider such that at least part thereof is exposed, and disposed to allow a display area to be expanded according to the withdrawing of the slider and allow the expanded display area to be hidden inside the housing; and a support body mounted closely in contact on a bottom face of the flexible display; and a smoothness maintaining device of the expanded display area when the slider is withdrawn, wherein the smoothness maintaining device comprises: at least one first roller rotatably disposed at a first position of the housing; and a second roller facing away from the first roller, and rotatably disposed at a second position of the housing; characterised in that the housing comprises an anti-scratch device of the expanded display area, in proximity to the second roller; and wherein the anti-scratch device is disposed to a lower end of the housing, and is configured as at least one anti-friction member disposed to face at least part of an outer circumferential face of the second roller. a housing including a first cover disposed to face a first direction, a second cover disposed to face a second direction opposite to the first direction, and a side member enclosing at least part of a space between the first and second covers; a slider to be inserted or withdrawn by being disposed to at least part of an area of the first cover of the housing; a flexible display disposed in the slider such that at least part thereof is exposed, and disposed to allow a display area to be expanded according to the withdrawing of the slider and allow the expanded display area to be hidden inside the housing; and a support body mounted closely in contact on a bottom face of the flexible display; and a smoothness maintaining device of the expanded display area when the slider is withdrawn, wherein the smoothness maintaining device comprises: at least one first roller rotatably disposed at a first position of the housing; and a second roller facing away from the first roller, and rotatably disposed at a second position of the housing; characterised in that the housing comprises an anti-scratch device of the expanded display area, in proximity to the second roller; and wherein the anti-scratch device is disposed to a lower end of the housing, and is configured as at least one anti-friction member disposed to face at least part of an outer circumferential face of the second roller. at least one first roller rotatably disposed at a first position of the housing; and a second roller facing away from the first roller, and rotatably disposed at a second position of the housing; characterised in that the housing comprises an anti-scratch device of the expanded display area, in proximity to the second roller; and wherein the anti-scratch device is disposed to a lower end of the housing, and is configured as at least one anti-friction member disposed to face at least part of an outer circumferential face of the second roller.