Without receiving the influence of the half shadow, the multiple leaf collimator which can form the radiation field whose contrast is high and that the corpuscular ray remedy device is obtained are designated as purpose. Gathering one end aspect (E L), of the plural leaf boards (5L) it arranges into thickness direction the leaf line (5C) and the leaf board (5L) which vis-a-vis respectively, vis-a-vis the beam axis (X B), drives to approach or estrangement direction the leaf board drive (5D) which and, has one end aspect (E L), as for each one of the leaf board (5L), vis-a-vis the particular leaf board, to thickness direction it adjoins the opposition aspect (PL) of the leaf board which, the 1st axis on the beam axis (X B) (Asa) with the plane surface (P Sa) which is included it is formed, leaf board drive (5D), the beam axis (X B) on the beam axis (X B) and paralleling to the circumferential track (O L) which centers the 2nd axis (A sb) which is vertical to the 1st axis (A sa), drives the leaf board (5L).半影の影響を受けずに、コントラストの高い照射野が形成できるマルチリーフコリメータおよび粒子線治療装置を得ることを目的とする。複数のリーフ板(5L)の一端面(EL)を揃えて厚み方向に並べたリーフ列(5C)と、リーフ板(5L)のそれぞれに対して、一端面(EL)をビーム軸(XB)に対して接近または離反方向に駆動させるリーフ板駆動機構(5D)と、を備え、リーフ板(5L)のそれぞれは、当該リーフ板に対して厚み方向に隣接するリーフ板との対向面(PL)が、ビーム軸(XB)上の第1の軸(Asa)を含む平面(PSa)で形成され、リーフ板駆動機構(5D)は、ビーム軸(XB)上のビーム軸(XB)および第1の軸(Asa)に垂直な第2の軸(Asb)を中心とする円周軌道(OL)に沿ってリーフ板(5L)を駆動する。
