A vertical bus supporting device for a switchboard that includes, in a housing thereof, a plurality of vertical buses, a plurality of horizontal buses, and a plurality of functional units obtained by unitizing control devices, the vertical bus supporting device comprising: vertical bus supporting tools each including two vertical bus supports disposed so as to hold therebetween the plurality of vertical buses from a front-surface side and a rear-surface side, respectively, and vertical bus supporting metal members disposed so as to couple the two vertical bus supports from rear surfaces of the two respective vertical bus supports; and vertical bus protective covers made of an insulating material and mounted to the vertical bus supporting tools, each vertical bus protective cover including partition walls configured to surround and insulate the plurality of vertical buses, wherein the plurality of the vertical bus supporting tools is configured to be located so as not to interfere with contactors, of the functional units, which are connected to the plurality of vertical buses, the vertical bus supporting tools being arrangeable such that intervals are kept therebetween in a longitudinal direction of the plurality of vertical buses, and wherein the vertical bus protective covers are arranged between the respective vertical bus supporting tools; wherein each vertical bus protective cover is mounted to each of the two corresponding vertical bus supports by fitting insertion portions and engagement portions with each other, wherein the insertion portions are formed on the vertical bus protective cover, wherein the engagement portions are formed on each of the two vertical bus supports; wherein an external shape of the insertion portions is a cylindrical shape and each end portion thereof has a smooth hemispheric shape having no acute-angle portion, and wherein each engagement portion has a smooth substantially circular shape having no acute-angle portion and tapered in the depth direction. vertical bus supporting tools each including two vertical bus supports disposed so as to hold therebetween the plurality of vertical buses from a front-surface side and a rear-surface side, respectively, and vertical bus supporting metal members disposed so as to couple the two vertical bus supports from rear surfaces of the two respective vertical bus supports; and two vertical bus supports disposed so as to hold therebetween the plurality of vertical buses from a front-surface side and a rear-surface side, respectively, and vertical bus supporting metal members disposed so as to couple the two vertical bus supports from rear surfaces of the two respective vertical bus supports; and vertical bus protective covers made of an insulating material and mounted to the vertical bus supporting tools, each vertical bus protective cover including partition walls configured to surround and insulate the plurality of vertical buses, wherein the plurality of the vertical bus supporting tools is configured to be located so as not to interfere with contactors, of the functional units, which are connected to the plurality of vertical buses, the vertical bus supporting tools being arrangeable such that intervals are kept therebetween in a longitudinal direction of the plurality of vertical buses, and wherein the vertical bus protective covers are arranged between the respective vertical bus supporting tools; wherein each vertical bus protective cover is mounted to each of the two corresponding vertical bus supports by fitting insertion portions and engagement portions with each other, wherein the insertion portions are formed on the vertical bus protective cover, wherein the engagement portions are formed on each of the two vertical bus supports; wherein an external shape of the insertion portions is a cylindrical shape and each end portion thereof has a smooth hemispheric shape having no acute-angle portion, and wherein each engagement portion has a smooth substantially circular shape having no acute-angle portion and tapered in the depth direction.