An object of this invention is to transport a charged particle beam having a distribution in which the particle-number variation at its end is moderate, without undesirably increasing the beam size. Assuming that a direction perpendicular to a traveling direction of the charged particle beam and passing from a center of the beam to its steep portion is an x-direction, a beam shaping device (10) included in a beam transport system (30) is provided with: a pre- stage quadrupole electromagnet (3) that reduces a distribution width of x-angle components (x) that are inclinations in the x-direction of the charged particles in the beam with respect to the traveling direction a penumbra expander (1) that moderates an end profile of a particle-number distribution of the x-angle components (x) in the beam having passed through the pre-stage quadrupole electromagnet (3) and a post-stage quadrupole electromagnet (4) that adjusts a betatron phase in a phase-space distribution in the x-direction, of the beam having passed through the penumbra expander (1) wherein the post-stage quadrupole electromagnet (4) adjusts a phase advance angle of the betatron phase from the penumbra expander (1) to the isocenter (IC), to be in a range of an odd multiple of 90° ± 45°.
