An aircraft control device that is configured to calculate a trajectory of an aircraft of a plurality of aircrafts that are members of a flight, by using a calculation method in which a solution is obtained by discretizing a continuous variable of a continuous problem, which is a time function, the aircraft control device comprising: a role determination means that is configured to: (a) determine a role of the aircraft, the role being one of searching and tracking of a target, guiding of a guided missile and shooting of a guided missile; (b) assign an indicator variable to each of an objective function and a constraint both used for determining a trajectory of the aircraft, the objective function including a function for calculating a distance between the aircraft and the target, and (c) determine a value of the indicator variable for every objective function and every constraint, such that an objective function and a constraint that do not correspond to the determined role of the aircraft are invalidated and not used for determining an optimal trajectory of the aircraft, a trajectory determination means (52, 54) that is configured to: (a) calculate discrete points (t1, tN) indicating a trajectory of the aircraft by substituting a discretized control variable of the aircraft into an equation of motion of the aircraft, and (b) determine, from among the trajectories that satisfy the constraint corresponding to the role of the aircraft, the optimal trajectory based on an evaluation value obtained by the objective function corresponding to the role of the aircraft; wherein, if the role of the aircraft is searching and tracking of a target, the constraint is to constantly acquire and track the target within a coverage area of a radar, wherein, if the role of the aircraft is guiding of a guided missile, the constraint is to constantly acquire and track the target within a coverage area of a guidance radio wave, and wherein, if the role of the aircraft is shooting of a guided missile, the constraint is that a nose of the aircraft is pointed toward the target when the guided missile is shot, and that the target is within a range of the guided missile when the guided missile is shot; wherein the role and the optimal trajectory of the aircraft are determined concurrently. a role determination means that is configured to: (a) determine a role of the aircraft, the role being one of searching and tracking of a target, guiding of a guided missile and shooting of a guided missile; (b) assign an indicator variable to each of an objective function and a constraint both used for determining a trajectory of the aircraft, the objective function including a function for calculating a distance between the aircraft and the target, and (c) determine a value of the indicator variable for every objective function and every constraint, such that an objective function and a constraint that do not correspond to the determined role of the aircraft are invalidated and not used for determining an optimal trajectory of the aircraft, (a) determine a role of the aircraft, the role being one of searching and tracking of a target, guiding of a guided missile and shooting of a guided missile; (b) assign an indicator variable to each of an objective function and a constraint both used for determining a trajectory of the aircraft, the objective function including a function for calculating a distance between the aircraft and the target, and (c) determine a value of the indicator variable for every objective function and every constraint, such that an objective function and a constraint that do not correspond to the determined role of the aircraft are invalidated and not used for determining an optimal trajectory of the aircraft, a trajectory determination means (52, 54) that is configured to: (a) calculate discrete points (t1, tN) indicating a trajectory of the aircraft by substituting a discretized control variable of the aircraft into an equation of motion of the aircraft, and (b) determine, from among the trajectories that satisfy the constraint corresponding to the role of the aircraft, the optimal trajectory based on an evaluation value obtained by the objective function corresponding to the role of the aircraft; (a) calculate discrete points (t1, tN) indicating a trajectory of the aircraft by substituting a discretized control variable of the aircraft into an equation of motion of the aircraft, and (b) determine, from among the trajectories that satisfy the constraint corresponding to the role of the aircraft, the optimal trajectory based on an evaluation value obtained by the objective function corresponding to the role of the aircraft; wherein, if the role of the aircraft is searching and tracking of a target, the constraint is to constantly acquire and track the target within a coverage area of a radar, wherein, if the role of the aircraft is guiding of a guided missile, the constraint is to constantly acquire and track the target within a coverage area of a guidance radio wave, and wherein, if the role of the aircraft is shooting of a guided missile, the constraint is that a nose of the aircraft is pointed toward the target when the guided missile is shot, and that the target is within a range of the guided missile when the guided missile is shot; wherein the role and the optimal trajectory of the aircraft are determined concurrently.