A scanning candidate route extracting unit which extracts plural candidates of scanning routes in which each of the scanning routes connects all spot positions in one layer is provided, in an evaluation function using necessary scanning time Tk and weight coefficient wk for a kth partial route among partial routes which are routes between the spot positons which are adjacent on one of the plural candidates of scanning routes, and number n of spot in the layer, wk with respect to a partial route which passes through affected tissue is set to be 1, wk with respect to a partial route which passes through normal tissue is set to be bigger than 1, and wk with respect to a partial route which passes through an important internal organ is set to be bigger than wk with respect to a partial route which passes through normal tissue.
