To provide an accelerator control method, an accelerator control device, and a particle beam treatment system, which are capable of making an acceleration cycle shorter.SOLUTION: In an accelerator control method according to the present embodiment, current is supplied, on the basis of a current value command signal, to a plurality of deflection electromagnets, the current causing a magnetic field to be generated circulating around the interior of a main accelerator in accordance with an acceleration energy of charged particles. In the case of an acceleration cycle involving the emission of charged particles to a beam transport system, a flat region that causes the current value of the deflection electromagnets to be constant is provided. In the case of an acceleration cycle not involving the emission of charged particles to the beam transport system, the flat region is not provided in the current value command signal, and the time change of the current value is smoothed when transitioning to the flat region of the current value or when transitioning from the flat region of the current value. The time required for smoothing is determined on the basis of a prescribed take-out energy of the charged particles, or on the basis of the difference in energy before and after a change to the prescribed take-out energy.SELECTED DRAWING: Figure 1【課題】加速サイクルをより短くすることが可能な加速器の制御方法、加速器の制御装置、及び粒子線治療システムを提供する。【解決手段】本実施形態による加速器の制御方法は、電流値の指令信号に基づき、荷電粒子の加速エネルギに応じて主加速器内を周回させる磁場を発生させる電流を複数の偏向電磁石に供給する加速器の制御方法であって、ビーム輸送系への荷電粒子の出射を伴う加速サイクルの場合には、偏向電磁石の電流値を一定にさせるフラット領域を設け、ビーム輸送系への荷電粒子の出射を伴わない加速サイクルの場合には、電流値の指令信号に、フラット領域を設けず、電流値のフラット領域への移行時、またはフラット領域からの移行時に電流値の時間変化を平滑化させ、平滑化に要する時間を、荷電粒子の所定の取り出しエネルギ、または、所定の取り出しエネルギへの変更前後のエネルギの差に基づいて決定する。【選択図】図１
