A replenishment planning device calculates a first route replenishment point on a travel route at which replenishment of a chemical becomes necessary, a second route replenishment point on the travel route which is closer to a replenishment area than the first route replenishment point is, and first and second times necessary for an unmanned helicopter to travel from a travel start point, via the first and the second route replenishment points, to a replenishment area to have the chemical replenished, and to move back to the travel route. Thereafter, a process takes the first and the second route replenishment points as next travel start points, and calculates, for each, next first and second route replenishment points, and first and second times, and is repeated for each replenishment plan pattern until the first route replenishment point reaches a travel end point, such that position information and time information for each replenishment plan pattern are generated.