A particle beam treatment device includes an irradiation nozzle which moves a particle beam in a direction which is perpendicular to an advancing direction a dose monitor which measures the dose of the particle beam a planning part which sets the irradiation dose applied to a target volume and a controlling part which controls the irradiation dose applied to a target volume based on irradiation dose set value which is set by a value measured by the dose monitor and the planning part, wherein the planning part stores the absorbed dose distribution data in the depth direction which is prepared in advance using the absorbed dose at the reference depth which is a predetermined position nearer to an incident side of the particle beam than the position of Bragg peak as the reference and calculates the irradiation dose set value using the absorbed dose at the reference depth.
