An information processing device comprises: an acquisition unit that acquires an image which includes a facial image region and in which an image of a person who goes into a gate is captured from the direction from the exit to the entrance; a processing unit that performs a second facial authentication process for a person for whom a first facial authentication process has been successful, the first facial authentication process being based on a first image captured in a first area, and the second facial authentication process being based on a second image captured in a second area between the exit of the gate and the first area; and an output unit that, when the person for whom the first facial authentication process has been successful and a person in the second image are determined to be identical, outputs that the person has passed through the gate.