1. An annotation addition method of adding one or more annotations into an input medium file, comprising: an annotation detection model creation step of creating one or more annotation detection models based on one or more training samples formed by one or more existing media files having one or more annotations; an annotation coexistence coefficient extraction step of extracting one or more coexistence coefficients of any two annotations based on appearance frequencies of the annotations in the training samples; a medium file input step of inputting the input medium file; a sense-of-vision feature extraction step of extracting one or more sense-of-vision features from the input medium file; an initial annotation obtaining step of obtaining one or more initial annotations of the input medium file; a candidate annotation acquiring step of acquiring one or more candidate annotations based on the initial annotations and the coexistence coefficients of the annotations in the training samples; and a final annotation set selection step of selecting a final annotation set suitable for describing content of the input medium file from the candidate annotations based on the sense-of-vision features of the input medium file and the coexistence coefficients by using the annotation detection models.