Impact energy absorbing structure in upper portion of motor vehicle body

In a structure for absorbing energy in an upper portion of a motor vehicle body, an energy absorbing body is disposed between a roof side rail and a roof lining. The energy absorbing body is a resin-made rib member having three longitudinal ribs and transverse ribs that are more in number than the longitudinal ribs. The three longitudinal ribs are formed so as to compensate for a reduced amount of displacement that is allowed for a longitudinal rib for a purpose of energy absorption in a section of the energy absorbing body taken on an imaginary plane extending along at least one of the transverse ribs, by varying at least one of a pitch between two longitudinal ribs provided adjacent to each other in the section, an angle formed by each longitudinal rib with respect to an imaginary horizontal plane in the section, and a thickness of each longitudinal rib.