1. A ranking information preparation apparatus for preparing ranking information on ranking regarding importance of each of a series of inputted moving pictures, comprising: image coding means for receiving the moving picture to output a coded image obtained by coding the moving picture and extracting predetermined feature parameters produced upon the coding to be outputted; feature vector computation means for receiving said feature parameters to output feature vectors of image frames defined in n dimensions; and curve simplification means for simplifying loci generated by arranging said n-dimensional feature vectors outputted by said feature vector computation means in time series manner to output the ranking information on ranking regarding importance of each of the series of moving pictures.