A target container built in a neutron scattering apparatus and containing a target material, e.g. a liquid metal has a beam window part of a thin structure through which a proton beam enters and which withstands against the stress due to pressure wave, the thermal stress, and the like. The target container has a double structure of inner and outer tubes spaced apart specifically and each having a beam window part that has a front face on which a proton beam impinges, wherein a cooling material is supplied between the inner and outer tubes and the target material is supplied inside the inner tube. The beam window part of the inner tube has a flat plate structure in order to lower the rigidity and to reduce the secondary stress generated in the target container by a pressure wave. Alternatively, the beam window part of the inner tube has a straight line longitudinal section to endure the pressure wave stress and a continuous curve lateral section to endure the thermal stress.