Herein disclosed an information processing apparatus including converting means and retrieval means, wherein the converting means converts content feature quantities using functions adapted to convert a plurality of feature quantities attached to a plurality of pieces of content so that the distance between pieces of content defined by the plurality of feature quantities coincides with the distance suited for a user-entered similarity relationship between the plurality of pieces of content, the functions being further adapted to map the pieces of content laid out in a feature quantity space defined by the plurality of feature quantities into a new feature quantity space by the conversion of the plurality of feature quantities, and wherein the retrieval means retrieves similar pieces of content based on converted feature quantities.