There is provided a method of arranging, as a composite charged-particle beam system, a gas ion beam apparatus, an FIB and an SEM in order to efficiently prepare a TEM sample. The composite charged-particle beam system includes an FIB lens-barrel 1, an SEM lens-barrel 2, a gas ion beam lens-barrel 3, and a rotary sample stage 9 having an eucentric tilt mechanism and a rotating shaft 10 orthogonal to an eucentric tilt axis 8. In the composite charged-particle beam system, an arrangement is made such that a focused ion beam 4, an electron beam 5 and a gas ion beam 6 intersect at a single point, an axis of the FIB lens-barrel 1 and an axis of the SEM lens barrel 2 are orthogonal to the eucentric tilt axis 8, respectively, and the axis of the FIB lens-barrel 1, an axis of the gas ion beam lens-barrel 3 and the eucentric tilt axis 8 are in one plane.