A trajectory generation device includes a storage unit that stores a plurality of trajectories; a trajectory acquisition unit that acquires a trajectory, corresponding to an environment similar to a current environment, from the plurality of trajectories stored in the storage unit; and a trajectory generation unit that calculates a longest trajectory part, which is present in a moving object moving area in the trajectory acquired by the trajectory acquisition unit, and generates a trajectory by connecting both ends of the calculated longest trajectory part to a predetermined start point and a predetermined end point respectively.