1. An image retrieval apparatus for extracting a frame of moving image data as still image data, comprising: a character string input unit configured to input a character string to be retrieved; a search unit configured to retrieve frames having the character string input by said character string input unit from moving image data including a plurality of frames; and an image extraction unit configured to extract, if frames having the character string in an equivalent position, which are retrieved by said search unit, are consecutive for a predetermined amount, one of the consecutive frames as still image data.