A side body vehicle structure for a vehicle, comprising: a side sill extending in a vehicle longitudinal direction; and side doors positioned above the side sill and configured to cover freely openably and closably an opening or a doorway for passenger ingress and egress, wherein the side doors include a rear door configured to cover a rear part of the opening or doorway, wherein the side sill has an upper flange portion, which, in a vertical cross section along the vehicle width direction, includes a portion of a side sill outer member that is raised upward and a portion of a side sill inner member that is raised upward, wherein the upper flange portion includes a rear door facing flange portion configured to face the rear door in the vehicle width direction, and a front door facing flange portion being forward of the rear door facing flange portion, wherein the rear door facing flange portion is formed in a shape having a length in the vehicle vertical direction longer than a length of the front door facing flange portion in the vehicle vertical direction, and wherein a gusset member is provided, which, in a vertical cross section along the vehicle width direction, has an upper end joined to the rear door facing flange portion and is configured to form a closed cross section with the side sill inner member, characterized in that the gusset member is joined to an inner upper flange portion forming the upper flange portion, the gusset member is joined to an inner upper surface part of the side sill inner member, the gusset member is formed so as to be a closed cross sectional shape with the inner upper flange portion and the inner upper surface part, the gusset member is formed integrally by a gusset upper surface part having an upper j oint part j oined to the inner upper flange portion, a lower joint part joined to an inner side surface part extending toward a lower part of the vehicle from an edge of an inside in the vehicle width direction on the inner upper surface part, a bulged part bulging toward an upper part of the vehicle between the upper joint part and the lower joint part, and the bulged part of the gusset upper surface part is formed so as to be a closed cross sectional shape that is approximately triangular in a front view with the inner upper flange portion and the inner upper surface part in the vertical cross section along the vehicle width direction. a side sill extending in a vehicle longitudinal direction; and side doors positioned above the side sill and configured to cover freely openably and closably an opening or a doorway for passenger ingress and egress, wherein the side doors include a rear door configured to cover a rear part of the opening or doorway, wherein the side sill has an upper flange portion, which, in a vertical cross section along the vehicle width direction, includes a portion of a side sill outer member that is raised upward and a portion of a side sill inner member that is raised upward, wherein the upper flange portion includes a rear door facing flange portion configured to face the rear door in the vehicle width direction, and a front door facing flange portion being forward of the rear door facing flange portion, wherein the rear door facing flange portion is formed in a shape having a length in the vehicle vertical direction longer than a length of the front door facing flange portion in the vehicle vertical direction, and wherein a gusset member is provided, which, in a vertical cross section along the vehicle width direction, has an upper end joined to the rear door facing flange portion and is configured to form a closed cross section with the side sill inner member, characterized in that the gusset member is joined to an inner upper flange portion forming the upper flange portion, the gusset member is joined to an inner upper surface part of the side sill inner member, the gusset member is formed so as to be a closed cross sectional shape with the inner upper flange portion and the inner upper surface part, the gusset member is formed integrally by a gusset upper surface part having an upper j oint part j oined to the inner upper flange portion, a lower joint part joined to an inner side surface part extending toward a lower part of the vehicle from an edge of an inside in the vehicle width direction on the inner upper surface part, a bulged part bulging toward an upper part of the vehicle between the upper joint part and the lower joint part, and the bulged part of the gusset upper surface part is formed so as to be a closed cross sectional shape that is approximately triangular in a front view with the inner upper flange portion and the inner upper surface part in the vertical cross section along the vehicle width direction.