The present invention aims to transport a charged particle beam with a distribution having moderate variation in particle number at an end portion thereof, without increasing the beam size to an unnecessary extent. A beam transport system (30) comprises a beam shaping device (10). The beam shaping device (10) comprises: an front quadrupole electromagnet (3) for reducing the distribution width of x angular component (x’) which is the slope of the travel direction of the charged particles of beam with respect to the x direction, provided that a direction perpendicular to a travel direction of charged beam is defined as x direction, a penumbra amplifier (1) for moderating the end shape of the particle number distribution of the x angular component (x’) of the beam passing the front quadrupole electromagnet (3), and a back quadrupole electromagnet (4) for adjusting the phase of a betatron of the phase space in the x direction of the beam passing through the penumbra amplifier (1), wherein, the back quadrupole electromagnet (4) is for adjusting the phase proceeding angle of the betatron from the penumbra amplifier (1) to the isocenter (IC) to be within a range of n×90°± 45°, wherein n is an odd number.本發明之目的為不會將射束尺寸增大為不必要的程度,而可輸送其端部之粒子數的變化和緩之分布的帶電粒子射束。射束輸送系統(30)所具備之射束整形裝置(10)係具備:前段四極電磁鐵(3),當將垂直於帶電粒子射束的行進方向且從射束的中心通過急端部的方向定為x方向時,前段四極電磁鐵(3)係將射束中之帶電粒子之相對於x方向之行進方向之斜率的x角度成分(x’)的分布寬度減小;半影放大器(1),用以使通過前段四極電磁鐵(3)之射束中之x角度成分(x’)之粒子數分布的端部形狀和緩;及後段四極電磁鐵(4),用以調整通過半影放大器(1)之射束之x方向之相位空間分布中的β加速器相位;後段四極電磁鐵(4)係用以將從半影放大器(1)至等中心(IC)的β加速器相位的相位進角調整為90度的奇數倍數±45度的範圍。1‧‧‧半影放大器2‧‧‧四極電磁鐵3‧‧‧前段四極電磁鐵4‧‧‧後段四極電磁鐵6‧‧‧散射體9‧‧‧射束路徑10‧‧‧射束整形裝置30‧‧‧射束輸送系統IC‧‧‧等中心
