A lower structure of an electric vehicle comprising: a floor panel that is provided with a floor tunnel extending in a vehicle front-rear direction; a tunnel side frame that is arranged below the floor panel in the vehicle and is arranged at at least one side portion in a vehicle width direction of the floor tunnel; a floor side frame that is arranged below the floor panel in the vehicle and is arranged on an outer side in the vehicle width direction of the tunnel side frame; a battery unit that is arranged below the floor panel in the vehicle and is arranged between the tunnel side frame and the floor side frame in the vehicle width direction; and an attachment bracket that is formed to extend from the tunnel side frame to the floor side frame along the vehicle width direction and connects the battery unit to the tunnel side frame and the floor side frame, characterized in that the attachment bracket has: a lower wall portion that supports a bottom portion of the battery unit; an outer vertical wall portion that extends upward from an end portion on a vehicle outer side of the lower wall portion and is connected to the floor side frame; and an inner vertical wall portion that extends upward from an end portion on a vehicle inner side of the lower wall portion and is connected to the tunnel side frame, and a position of the connection between the inner vertical wall portion and the tunnel side frame is located higher in the vehicle than a position of the connection between the outer vertical wall portion and the floor side frame. a floor panel that is provided with a floor tunnel extending in a vehicle front-rear direction; a tunnel side frame that is arranged below the floor panel in the vehicle and is arranged at at least one side portion in a vehicle width direction of the floor tunnel; a floor side frame that is arranged below the floor panel in the vehicle and is arranged on an outer side in the vehicle width direction of the tunnel side frame; a battery unit that is arranged below the floor panel in the vehicle and is arranged between the tunnel side frame and the floor side frame in the vehicle width direction; and an attachment bracket that is formed to extend from the tunnel side frame to the floor side frame along the vehicle width direction and connects the battery unit to the tunnel side frame and the floor side frame, characterized in that the attachment bracket has: a lower wall portion that supports a bottom portion of the battery unit; an outer vertical wall portion that extends upward from an end portion on a vehicle outer side of the lower wall portion and is connected to the floor side frame; and an inner vertical wall portion that extends upward from an end portion on a vehicle inner side of the lower wall portion and is connected to the tunnel side frame, and a lower wall portion that supports a bottom portion of the battery unit; an outer vertical wall portion that extends upward from an end portion on a vehicle outer side of the lower wall portion and is connected to the floor side frame; and an inner vertical wall portion that extends upward from an end portion on a vehicle inner side of the lower wall portion and is connected to the tunnel side frame, and a position of the connection between the inner vertical wall portion and the tunnel side frame is located higher in the vehicle than a position of the connection between the outer vertical wall portion and the floor side frame.