Disclosed is an electronic device that includes a first housing and a second housing, a first hinge structure including a first hinge housing, first and second hinge connecting parts, first and second gears, first and second idle gears, at first support that rotatably supports the first gear and the first idle gear, and a second support that rotatably supports the second gear and the second idle gear, a second hinge structure including a second hinge housing, third and fourth hinge connecting parts, third and fourth gears, third and fourth idle gears, a third support that rotatably supports the third gear and the third idle gear, and a fourth support that rotatably supports the fourth gear and the fourth idle gear, wherein the first hinge structure and the second hinge structure allow the first housing and the second housing to rotate relative to each other between a first state and a second state, and a first surface faces a third surface in the first state, and a second surface faces a fourth surface in the second state.