An automated warehouse comprising: a plurality of shelves each configured to accommodate an article; a loading-and-unloading port where the article is loaded and unloaded; a first stacker crane configured to convey the article between the shelves and the loading-and-unloading port; and a traveling path on which the first stacker crane travels, wherein the first stacker crane includes a first traveling unit including a first traveling drive wheel configured to roll along the traveling path, a first mast vertically provided on the first traveling unit so as to overlap the first traveling drive wheel when viewed from a vertical direction, a first lifting platform arranged on one side in a travel direction with respect to the first mast and configured to ascend and descend along the first mast, a first transferring device provided to the first lifting platform, a first traveling motor configured to drive the first traveling drive wheel, and a first lifting motor configured to drive the first lifting platform 73a), wherein a housing is fixed to the lower end of the mast and rotatably supports the traveling drive wheel; the first traveling motor is fixed to the housing so as to protrude on the side of shelves of the racks and the fist lifting motor is attached to the housing so as to protrude on the side of the shelves of the rack wherein rack 3A and the rack 3B are provided so as to oppose each other, characterized in that the travelling unit 71a includes a pair of mast-side traveling guide wheels 81a and 81a, and in that - each mast-side traveling guide wheel 81a rolls along a side surface of the traveling rail 51, each mast-side traveling guide wheel 81 a is arranged so as to overlap the mast 72a when viewed from the vertical direction, the pair of the mast-side traveling guide wheels 81a and 81a hold the traveling rail 51 in the horizontal direction, and each mast-side traveling guide wheel 81 a is rotatably attached to a lower portion of the housing 77a. a plurality of shelves each configured to accommodate an article; a loading-and-unloading port where the article is loaded and unloaded; a first stacker crane configured to convey the article between the shelves and the loading-and-unloading port; and a traveling path on which the first stacker crane travels, wherein the first stacker crane includes a first traveling unit including a first traveling drive wheel configured to roll along the traveling path, a first mast vertically provided on the first traveling unit so as to overlap the first traveling drive wheel when viewed from a vertical direction, a first lifting platform arranged on one side in a travel direction with respect to the first mast and configured to ascend and descend along the first mast, a first transferring device provided to the first lifting platform, a first traveling motor configured to drive the first traveling drive wheel, and a first lifting motor configured to drive the first lifting platform 73a), wherein a housing is fixed to the lower end of the mast and rotatably supports the traveling drive wheel; the first traveling motor is fixed to the housing so as to protrude on the side of shelves of the racks and the fist lifting motor is attached to the housing so as to protrude on the side of the shelves of the rack wherein rack 3A and the rack 3B are provided so as to oppose each other, characterized in that the travelling unit 71a includes a pair of mast-side traveling guide wheels 81a and 81a, and in that - each mast-side traveling guide wheel 81a rolls along a side surface of the traveling rail 51, each mast-side traveling guide wheel 81 a is arranged so as to overlap the mast 72a when viewed from the vertical direction, the pair of the mast-side traveling guide wheels 81a and 81a hold the traveling rail 51 in the horizontal direction, and each mast-side traveling guide wheel 81 a is rotatably attached to a lower portion of the housing 77a. the first stacker crane includes a first traveling unit including a first traveling drive wheel configured to roll along the traveling path, a first mast vertically provided on the first traveling unit so as to overlap the first traveling drive wheel when viewed from a vertical direction, a first lifting platform arranged on one side in a travel direction with respect to the first mast and configured to ascend and descend along the first mast, a first transferring device provided to the first lifting platform, a first traveling motor configured to drive the first traveling drive wheel, and a first lifting motor configured to drive the first lifting platform 73a), wherein a housing is fixed to the lower end of the mast and rotatably supports the traveling drive wheel; the first traveling motor is fixed to the housing so as to protrude on the side of shelves of the racks and the fist lifting motor is attached to the housing so as to protrude on the side of the shelves of the rack wherein rack 3A and the rack 3B are provided so as to oppose each other, characterized in that the travelling unit 71a includes a pair of mast-side traveling guide wheels 81a and 81a, and in that - each mast-side traveling guide wheel 81a rolls along a side surface of the traveling rail 51, each mast-side traveling guide wheel 81 a is arranged so as to overlap the mast 72a when viewed from the vertical direction, the pair of the mast-side traveling guide wheels 81a and 81a hold the traveling rail 51 in the horizontal direction, and each mast-side traveling guide wheel 81 a is rotatably attached to a lower portion of the housing 77a.