The present invention relates to an expanding structure for a bench, which provides an expanded space on which a user can sit by being formed at intervals in a landscape unit providing a plant cultivation space and a sitting space by ascending from a footpath inside or outside a building. According to an embodiment of the present invention, the expanding structure for a bench includes: a first sitting unit including a vertical surface erect from the footpath and a horizontal surface extended from the vertical surface to the plant cultivation space； an expanding unit moving from the first sitting unit to the footpath in a first direction by being unwound by a first outer force while being accommodated in a first accommodation space dented from the vertical surface and wound in a second direction opposite to the first direction when the first outer force is released； and a hanging unit rotating in a first position, hidden in the footpath, by a second outer force and moved to a second position in which the hanging unit protrudes to the upper surface of the footpath. The expanding unit includes: a first fixing unit including a rotation shaft and fixed to the first accommodation space； a rotation unit rotating around the rotation shaft； and a bench unit wound on the outer surface of the rotation unit. The bench unit is coupled to the hanging unit at the second position while moving in the first direction and is unfolded from the first sitting unit to the hanging unit. The landscape unit includes a slope erect from the footpath, and the vertical surface has a different height from the slope of the landscape unit.본 발명의 일 실시예에 따른 벤치 확장 구조는, 건축구조물의 실내 또는 실외에서, 보행로로부터 상승되어 식물재배공간 및 착석공간을 제공하는 조경부에 이격되어 형성되어 사용자가 착석할 수 있는 확장된 공간을 제공하는 벤치 확장 구조에 있어서, 상기 보행로로부터 기립된 수직면 및 상기 수직면으로부터 상기 식물재배공간으로 연장된 수평면을 구비하는 제1 착석부, 상기 수직면으로부터 함입된 제1 수용공간에 수용된 채, 제1 외력에 의해 권출되어 상기 제1 착석부로부터 상기 보행로를 향한 제1 방향으로 위치 이동되며, 상기 제1 외력이 해제되면 상기 제1 방향의 반대방향인 제2 방향으로 권취되는 확장부 및 상기 보행로 내에 은닉된 제1 위치로부터 제2 외력에
