An abandoned item detection unit detects an abandoned item shown in an image taken by any of a plurality of imaging devices. A person identification unit specifies the image directly before or directly after the appearance of the abandoned item as an image of abandonment timing, and identifies at least one person shown in the image of abandonment timing as a target person. A person search unit searches for an image showing the target person from among the images respectively taken by any of the plurality of imaging devices. A result display unit outputs a display showing the movement of the target person on the screen of a user terminal on the basis of the imaging device that has taken each image showing the target person and the imaging time at which each image showing the target person was taken.