A foldable electronic device, comprising: a processor; a memory; a first housing having a first length; a second housing having a second length different than the first length; a flexible display coupled to the first housing and the second housing; and a hinge assembly coupled to the first housing and the second housing for relative rotation of the first housing and the second housing, the hinge assembly including: a slider; a lever attached to the slider; a set of gears (60, 181, 184) disposed on the slider; and a linkage member connecting the lever and the set of gears (60, 181, 184) together, wherein the slider further includes a shifting member that forms an extension of the slider to couple the slider to the lever, wherein the lever includes a first end portion connected to the shifting member and a second end portion connected to a surface of the first housing, and wherein a first end portion of an arm of the linkage member is connected to the lever at a position between the first and second end portions (221, 222) of the lever, and wherein a second end portion of the arm of the linkage member is connected to at least one gear of the set of gears (60, 181, 184) such that: upon the relative rotation occurring in a first direction by the second housing, the set of gears (60, 181, 184) rotates and causes translation of the linkage member which causes rotation of the lever around a connection between the first end portion of the lever and the shifting member to thereby translationally move the first housing in a first linear direction, and upon the relative rotation occurring in a second direction by the second housing, the set of gears (60, 181, 184) rotates and causes translation of the linkage member which causes rotation of the lever around the connection between the first end portion of the lever and the shifting member to thereby translationally move the first housing in a second linear direction, the second linear direction being opposite to the first linear direction. a processor; a memory; a first housing having a first length; a second housing having a second length different than the first length; a flexible display coupled to the first housing and the second housing; and a hinge assembly coupled to the first housing and the second housing for relative rotation of the first housing and the second housing, the hinge assembly including: a slider; a lever attached to the slider; a set of gears (60, 181, 184) disposed on the slider; and a linkage member connecting the lever and the set of gears (60, 181, 184) together, a slider; a lever attached to the slider; a set of gears (60, 181, 184) disposed on the slider; and a linkage member connecting the lever and the set of gears (60, 181, 184) together, wherein the slider further includes a shifting member that forms an extension of the slider to couple the slider to the lever, wherein the lever includes a first end portion connected to the shifting member and a second end portion connected to a surface of the first housing, and wherein a first end portion of an arm of the linkage member is connected to the lever at a position between the first and second end portions (221, 222) of the lever, and wherein a second end portion of the arm of the linkage member is connected to at least one gear of the set of gears (60, 181, 184) such that: upon the relative rotation occurring in a first direction by the second housing, the set of gears (60, 181, 184) rotates and causes translation of the linkage member which causes rotation of the lever around a connection between the first end portion of the lever and the shifting member to thereby translationally move the first housing in a first linear direction, and upon the relative rotation occurring in a second direction by the second housing, the set of gears (60, 181, 184) rotates and causes translation of the linkage member which causes rotation of the lever around the connection between the first end portion of the lever and the shifting member to thereby translationally move the first housing in a second linear direction, the second linear direction being opposite to the first linear direction. upon the relative rotation occurring in a first direction by the second housing, the set of gears (60, 181, 184) rotates and causes translation of the linkage member which causes rotation of the lever around a connection between the first end portion of the lever and the shifting member to thereby translationally move the first housing in a first linear direction, and upon the relative rotation occurring in a second direction by the second housing, the set of gears (60, 181, 184) rotates and causes translation of the linkage member which causes rotation of the lever around the connection between the first end portion of the lever and the shifting member to thereby translationally move the first housing in a second linear direction, the second linear direction being opposite to the first linear direction.