A flight path search device that is adapted to search for a flight path of an aircraft, from outside of an enemy region including an enemy forces point to a predetermined point within the enemy region, the flight path search device comprising: - a storage unit that is adapted to store map information of a predetermined range, and enemy force range information; - a grid divider that is adapted to divide the map information stored in the storage unit, into cells in grid form on a horizontal plane; - a score calculator that is adapted to calculate a score relating to an attack avoidance degree that indicates a likelihood of the aircraft being attacked by enemy forces when flying from a first cell (Cp) within the enemy region to a cell adjacent to the first cell (Cp), based on the map information and enemy force range information stored in the storage unit; - a cell calculator that is adapted to calculate a second cell (Cg) that is situated on an extension of a straight line connecting the enemy forces point and the first cell (Cp), and outside of the enemy region, the extension extending from the first cell (Cp) towards the second cell (Cg); - a searcher that is adapted to search for, among adjacent cells adjacent to the first cell (Cp) on the map information, an optimal cell to which to move from the first cell (Cp) when moving from the first cell (Cp) toward the second cell (Cg), based on the score calculated by the score calculator; and - an updater that is adapted to update the first cell (Cp) by setting the optimal cell as a new first cell (Cp), in a case where the optimal cell found by the searcher does not agree with the second cell (Cg), wherein the cell where the predetermined point is situated is set as the first cell (Cp), and the calculating of the second cell (Cg) by the cell calculator, the searching for the optimal cell by the searcher using the second cell (Cg), and the updating of the first cell (Cp) by the updater, are repeated until the optimal cell found by the searcher agrees with the second cell (Cg). - a storage unit that is adapted to store map information of a predetermined range, and enemy force range information; - a grid divider that is adapted to divide the map information stored in the storage unit, into cells in grid form on a horizontal plane; - a score calculator that is adapted to calculate a score relating to an attack avoidance degree that indicates a likelihood of the aircraft being attacked by enemy forces when flying from a first cell (Cp) within the enemy region to a cell adjacent to the first cell (Cp), based on the map information and enemy force range information stored in the storage unit; - a cell calculator that is adapted to calculate a second cell (Cg) that is situated on an extension of a straight line connecting the enemy forces point and the first cell (Cp), and outside of the enemy region, the extension extending from the first cell (Cp) towards the second cell (Cg); - a searcher that is adapted to search for, among adjacent cells adjacent to the first cell (Cp) on the map information, an optimal cell to which to move from the first cell (Cp) when moving from the first cell (Cp) toward the second cell (Cg), based on the score calculated by the score calculator; and - an updater that is adapted to update the first cell (Cp) by setting the optimal cell as a new first cell (Cp), in a case where the optimal cell found by the searcher does not agree with the second cell (Cg),