A planning apparatus (70) determines irradiation parameter data (67) for a charged particle irradiation system (1), which radiates charged particles generated by an ion source (2) to a target (80) by accelerating the charged particles by means of a linear accelerator (4) and a synchrotron (5). The planning apparatus is provided with: a planning program (73), which determines the irradiation parameter data (67) with respect to one target (80) by combining charged particles of a plurality of kinds of ion species； and a CPU (71) for executing the planning program. Consequently, the irradiation planning apparatus capable of performing irradiation with desirable dose distribution with respect to the target, the irradiation planning program, an irradiation plan determining method, and the charged particle irradiation system are provided.
