1. An image taking system comprising an image taking means which takes an image by an image taking, an objective body detecting means which detects a predetermined objective body from an image taken by the image taking means, a storage means which stores a detection history comprising a past result of detection of the objective body and a newest result of detection of the objective body, and a determination means which refers to the detection history and determines whether the objective body is to be handled as detected in the image obtained newest.