An information processing device for reproducing content data is provided. The information processing device includes a reproducing unit for reproducing content data; a sound image localization processing unit for sound image localization processing the content data to be reproduced by the reproducing unit so that a sound image by the content data localizes at an arbitrary localization position; and a control unit for moving the localization position of the sound image in response to change in reproduction state of the content data by the reproducing unit.