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 around the interior of a main accelerator in accordance with the 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 a beam transport system, a flat region is not provided in the current value command-signal, and the time change of the current value is smoothed when transitioning to a flat region of the current value or when transitioning from a 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.[課題]提供可讓加速週期更短的加速器的控制方法、加速器的控制裝置及粒子線治療系統。[技術內容]本實施例的加速器的控制方法，是依據電流值的指令訊號，使對應帶電粒子的加速能量在主加速器內周轉的磁場發生的電流供給至複數偏向電磁鐵的加速器的控制方法，當伴隨朝電子束傳輸系的帶電粒子的射出的加速週期的情況時，設置使偏向電磁鐵的電流值一定的平面領域，當不伴隨朝電子束傳輸系的帶電粒子的射出的加速週期的情況時，在電流值的指令訊號，不設置平面領域，當朝電流值的平面領域的移動時、或是在從平面領域的移動時將電流值的時間變化平滑化，將平滑化所需要的時間，依據帶電粒子的規定的取出能量、或是朝規定的取出能量的變更前後的能量的差決定。
