An image monitoring system having a plurality of imaging devices, comprising: an abandoned item detection unit which detects an abandoned item shown in an image taken by any of the plurality of imaging devices; a person identification unit which, in the case where said abandoned item has been detected, processes a sequence of images received from the imaging device that has taken the image from which the abandoned item has been detected in reverse order of time series from a point in time when the abandoned item was discovered so as to specify the image directly before the abandoned item had been placed, or processes the sequence of images in order of time series from a past point in time where it is clear that there is no abandoned item so as to specify the image directly after the abandoned item had been placed, and identifies at least one person shown in the specified image as a target person; a person search unit which searches for an image showing the target person from among the images respectively taken by the plurality of imaging devices; and a result display unit which outputs on a screen a display showing the movement of the target person on the basis of the imaging device that took each image showing the target person and an imaging time at which each image showing the target person was taken; characterized in that: the image monitoring system further comprises a personal feature value acquisition unit which acquires a personal feature value including a plurality of worn clothing feature values of the target person on the basis of the specified image, the person search unit searches for the image showing the target person on the basis of the personal feature value, and the person search unit has a plurality of weighing patterns where the weight given to each of the plurality of worn clothing feature values is differentiated, executes trials of the search by applying the respective weighing patterns, selects the weighing pattern that most distinguishes the resulting target person from other people, and executes the search by applying the selected weighing pattern. an abandoned item detection unit which detects an abandoned item shown in an image taken by any of the plurality of imaging devices; a person identification unit which, in the case where said abandoned item has been detected, processes a sequence of images received from the imaging device that has taken the image from which the abandoned item has been detected in reverse order of time series from a point in time when the abandoned item was discovered so as to specify the image directly before the abandoned item had been placed, or processes the sequence of images in order of time series from a past point in time where it is clear that there is no abandoned item so as to specify the image directly after the abandoned item had been placed, and identifies at least one person shown in the specified image as a target person; a person search unit which searches for an image showing the target person from among the images respectively taken by the plurality of imaging devices; and a result display unit which outputs on a screen a display showing the movement of the target person on the basis of the imaging device that took each image showing the target person and an imaging time at which each image showing the target person was taken; characterized in that: the image monitoring system further comprises a personal feature value acquisition unit which acquires a personal feature value including a plurality of worn clothing feature values of the target person on the basis of the specified image, the person search unit searches for the image showing the target person on the basis of the personal feature value, and the person search unit has a plurality of weighing patterns where the weight given to each of the plurality of worn clothing feature values is differentiated, executes trials of the search by applying the respective weighing patterns, selects the weighing pattern that most distinguishes the resulting target person from other people, and executes the search by applying the selected weighing pattern. the image monitoring system further comprises a personal feature value acquisition unit which acquires a personal feature value including a plurality of worn clothing feature values of the target person on the basis of the specified image, the person search unit searches for the image showing the target person on the basis of the personal feature value, and the person search unit has a plurality of weighing patterns where the weight given to each of the plurality of worn clothing feature values is differentiated, executes trials of the search by applying the respective weighing patterns, selects the weighing pattern that most distinguishes the resulting target person from other people, and executes the search by applying the selected weighing pattern.