1. A video retrieval method comprising the steps of: providing first representative frame images from an enquiry video specified by a user; calculating at least one feature of each of the first representative frame images; generating a code string serving as an enquiry video name for the enquiry video by replacing the calculated feature of each of the first representative frame images by a corresponding code assigned to the calculated feature; registering beforehand the enquiry video name; inputting a target video; extracting second representative frame images from the target video; calculating at least one feature of each of the second representative frame images; generating a code string serving as a target video name for the target video by replacing the calculated feature of each of the second representative frame images by a corresponding code assigned to the calculated feature; and matching the enquiry video name with the target video name.