A display device comprising: a display module; a support part on a rear surface of the display module and comprising a support plate and a plurality of support bars; a first case accommodating the display module and the support part; a second case movably combined with the first case so as to be moved in a direction away from or close to a sidewall of the first case along a first direction, the sidewall extending perpendicular to the first direction, the second case accommodating the display module and the support part; and a sub-support part under the support part so as to overlap a part of the support part, wherein two sides of each of the plurality of support bars are configured to be inserted into first guide grooves defined in inner surfaces of the first case, which face with each other in a second direction perpendicular to the first direction, and the plurality of support bars are configured to be moved along the first guide grooves, wherein each of the first guide grooves comprises: a first extension part extending in the first direction; a second extension part extending in the first direction and positioned lower than the first extension part in a third direction; and a curved part extending from one side of the first extension part to one side of the second extension part, wherein the one side of each of the first and second extension parts is disposed in the vicinity of the sidewall of the first case, and the curved part has a convexly curved shape toward the sidewall of the first case, wherein the second case is configured to be moved in the first direction, each of the plurality of support bars is configured to be moved along the curved part to be positioned in a portion of the first extension part, which is adjacent to the curved part, and the sub-support part is positioned under the support bars which are disposed in the portion of the first extension part, the portion is adjacent to the curved part. a display module; a support part on a rear surface of the display module and comprising a support plate and a plurality of support bars; a first case accommodating the display module and the support part; a second case movably combined with the first case so as to be moved in a direction away from or close to a sidewall of the first case along a first direction, the sidewall extending perpendicular to the first direction, the second case accommodating the display module and the support part; and a sub-support part under the support part so as to overlap a part of the support part, wherein two sides of each of the plurality of support bars are configured to be inserted into first guide grooves defined in inner surfaces of the first case, which face with each other in a second direction perpendicular to the first direction, and the plurality of support bars are configured to be moved along the first guide grooves, wherein each of the first guide grooves comprises: a first extension part extending in the first direction; a second extension part extending in the first direction and positioned lower than the first extension part in a third direction; and a curved part extending from one side of the first extension part to one side of the second extension part, wherein the one side of each of the first and second extension parts is disposed in the vicinity of the sidewall of the first case, and the curved part has a convexly curved shape toward the sidewall of the first case, wherein the second case is configured to be moved in the first direction, each of the plurality of support bars is configured to be moved along the curved part to be positioned in a portion of the first extension part, which is adjacent to the curved part, and the sub-support part is positioned under the support bars which are disposed in the portion of the first extension part, the portion is adjacent to the curved part. a first extension part extending in the first direction; a second extension part extending in the first direction and positioned lower than the first extension part in a third direction; and a curved part extending from one side of the first extension part to one side of the second extension part, wherein the one side of each of the first and second extension parts is disposed in the vicinity of the sidewall of the first case, and the curved part has a convexly curved shape toward the sidewall of the first case, wherein the second case is configured to be moved in the first direction, each of the plurality of support bars is configured to be moved along the curved part to be positioned in a portion of the first extension part, which is adjacent to the curved part, and the sub-support part is positioned under the support bars which are disposed in the portion of the first extension part, the portion is adjacent to the curved part.