In a trajectory information processing device (201) for acquiring from a trajectory of a spiral-shaped graphic easy for a person to enter the input information intended by the person, an input receiving unit (202) receives input of coordinate information of a trajectory, a closed curve acquisition unit (203) repeatedly acquires a closed curve wherein the trajectory crosses over the trajectory for the first time after the starting point and removes from the trajectory the closed curve and the curve preceding thereto for the coordinate information of a trajectory whose input was received, and a vortex information outputting unit (204) outputs changes in the time interval at which closed curves are acquired as information indicating the intensity of the vortex motion of the trajectory.