A system for tracking a moving object, by using particle filtering, the system comprising: a camera (10A, 10B) configured to photograph the object; and a particle filtering unit configured to perform the particle filtering; the particle filtering unit comprises: an initial arrangement module configured to arrange in a standby mode particles, in a standby-state, in a background included in an image photographed by the camera; a module configured to detect that an operating mode of the system changes from a standby mode to a tracking mode for performing a tracking process of the object, when the object appears in the image photographed by the camera and the likelihood of the particles initially arranged in the standby mode decreases; a rearrangement module configured to rearrange the particles with respect to the object included in the image, in accordance with the likelihood of the particles arranged in the standby mode; a module configured to cause the particles to follow the object, thereby performing a tracking process after the initial arrangement module has initially arranged the particles; a module configured to arrange particles preliminarily near the particles following the object in the tracking process, in order to cancel occlusion occurring after the rearrangement module initially arranged the particles; and a module configured to cause, in the tracking process, the preliminarily arranged particles to follow a new object that appears when the occlusion is cancelled. a camera (10A, 10B) configured to photograph the object; and a particle filtering unit configured to perform the particle filtering; the particle filtering unit comprises: an initial arrangement module configured to arrange in a standby mode particles, in a standby-state, in a background included in an image photographed by the camera; a module configured to detect that an operating mode of the system changes from a standby mode to a tracking mode for performing a tracking process of the object, when the object appears in the image photographed by the camera and the likelihood of the particles initially arranged in the standby mode decreases; a rearrangement module configured to rearrange the particles with respect to the object included in the image, in accordance with the likelihood of the particles arranged in the standby mode; a module configured to cause the particles to follow the object, thereby performing a tracking process after the initial arrangement module has initially arranged the particles; a module configured to arrange particles preliminarily near the particles following the object in the tracking process, in order to cancel occlusion occurring after the rearrangement module initially arranged the particles; and a module configured to cause, in the tracking process, the preliminarily arranged particles to follow a new object that appears when the occlusion is cancelled. an initial arrangement module configured to arrange in a standby mode particles, in a standby-state, in a background included in an image photographed by the camera; a module configured to detect that an operating mode of the system changes from a standby mode to a tracking mode for performing a tracking process of the object, when the object appears in the image photographed by the camera and the likelihood of the particles initially arranged in the standby mode decreases; a rearrangement module configured to rearrange the particles with respect to the object included in the image, in accordance with the likelihood of the particles arranged in the standby mode; a module configured to cause the particles to follow the object, thereby performing a tracking process after the initial arrangement module has initially arranged the particles; a module configured to arrange particles preliminarily near the particles following the object in the tracking process, in order to cancel occlusion occurring after the rearrangement module initially arranged the particles; and a module configured to cause, in the tracking process, the preliminarily arranged particles to follow a new object that appears when the occlusion is cancelled.