PURPOSE: To reduce the size and the weight of the airframe of a flying object on which an air turbo-ramjet engine is mounted and to reduce the incurring of a pressure loss of suction air.

CONSTITUTION: A fuel gas generator 120 is arranged in a center body 2 and a fuel piping 31 through which liquid fuel is fed from a liquid fuel feeding deice 30, arranged on the outside of a duct 1, to a fuel gas generator 120 is inserted in a support member 106. Since a space in which the fuel gas generator 120 is contained is not needed on the airframe of a flying object on which an air turbo-ramjet engine 100 is mounted, the size and the weight of the airframe are reduced. Further, the fuel piping 31 is a piping through which liquid fuel is fed and since the diameter thereof is reduced, the size of a support member 106 is reduced and the fuel piping is prevented from being an obstacle on the flow of suction air and a pressure loss thereof is reduced.