Abstract: An authentication method and an input device are provided in which a password which a user has inputted in person can be easily reproduced, and it is unlikely for a password leak to occur even when peeped at. An authentication password includes position identification information disposed in an arbitrary position in an input section of an input device. Position identification information corresponding to a first indicated position of an input trajectory inputted from the input section is acquired. Based on the input trajectory, trajectory information representing repetitions of the trajectory from the first indicated position and movement information representing a movement direction with respect to the first indicated position are calculated.