A car body, in which a hollow shape stock composed of two face plates and ribs joining the face plates together is used to form a side body, and stresses are reduced while minimizing an increase in mass. A car body, comprising a hollow shape stock composed of two face plates (31, 31) and ribs (32) joining the face plates together and used to form a side body (11), wherein face plate portions (31c, 31d) in regions (B, D) above and below connection points (c) between circular arcs, which constitute corner portions of a window (15), and vertical sides of the window (15) are greater in thickness than in the remaining regions (A, C, E). Stresses are most heavily concentrated in the regions (B, D). Therefore, it is possible to achieve reduction in mass and enhancement in strength together. Further, buckling preventive tools can be arranged in spaces in the regions (B, D) of the hollow shape stock. Further, with the hollow shape stock (18) in a pier panel, face plates on an internal side are greater in thickness than those on an external side.