an upper main body extending in a longitudinal direction from two opposite sides of the vehicle, the upper main body comprising a plurality of transverse members;

a plurality of upper body pillar units each comprising a central portion bent and protruding upward and two opposite ends respectively connected to two opposite sides of the upper main body, the plurality of upper body pillar units being disposed to be spaced apart from one another in the longitudinal direction; and

an upper body connection member extending in the longitudinal direction of the vehicle, spaced apart upward from a side of the upper main body, and connecting sides of the plurality of upper body pillar units, wherein each of the upper body pillar units comprises pillar unit connection members connecting two opposite sides of the upper body pillar unit by being bent and protruding toward a front or rear side of the vehicle.