A portable information processing apparatus comprising: a replay processing unit that is arranged to replay content data; a synchronous display unit that is arranged to select pieces of associated information from a plurality of pieces of associated information contained in associated data corresponding to the content data, each said piece of associated information being associated with a corresponding portion of the content data for synchronous display of that piece of associated information with replay of its corresponding portion of the content data, and to instruct to display the selected pieces of associated information sequentially in synchronisation with the replay of the corresponding content data portions; and an output controlling unit that is arranged to display the associated information that is selected by the synchronous display unit in an associated information display area arranged in a display unit, wherein upon accepting an operation requesting to display a piece of associated information other than that corresponding to the replayed portion of the content data out of the pieces of the associated information contained in the associated data corresponding to the content data, the synchronous display unit is configured to select the piece of associated information other than that corresponding to the replayed portion based on the operation and instruct the output controlling unit to sequentially display the piece of associated information other than that corresponding to the replayed portion of the content data asynchronously with the replay of the content data, and the replay processing unit is configured to continue the replay of the replayed portion of the content data independently of the display of the associated information, further wherein the synchronous display unit is configured to end selecting the piece of associated information other than that corresponding to the replayed portion, when a predetermined time elapses after the piece of associated information other than that corresponding to the replayed portion is selected, the output controlling unit is configured to automatically switch displayed associated information, after the predetermined time has elapsed, from the piece of associated information other than that corresponding to the replayed portion to the piece of associated information corresponding to the replayed portion of the content data of the time after the predetermined time has elapsed, and the content data is audio data and the associated information is lyrics, chord names representing chord sounds, musical scales, musical symbols used in a score and/or symbols representing who is to sing parts in music. a replay processing unit that is arranged to replay content data; a synchronous display unit that is arranged to select pieces of associated information from a plurality of pieces of associated information contained in associated data corresponding to the content data, each said piece of associated information being associated with a corresponding portion of the content data for synchronous display of that piece of associated information with replay of its corresponding portion of the content data, and to instruct to display the selected pieces of associated information sequentially in synchronisation with the replay of the corresponding content data portions; and an output controlling unit that is arranged to display the associated information that is selected by the synchronous display unit in an associated information display area arranged in a display unit, wherein upon accepting an operation requesting to display a piece of associated information other than that corresponding to the replayed portion of the content data out of the pieces of the associated information contained in the associated data corresponding to the content data, the synchronous display unit is configured to select the piece of associated information other than that corresponding to the replayed portion based on the operation and instruct the output controlling unit to sequentially display the piece of associated information other than that corresponding to the replayed portion of the content data asynchronously with the replay of the content data, and the replay processing unit is configured to continue the replay of the replayed portion of the content data independently of the display of the associated information, further wherein the synchronous display unit is configured to end selecting the piece of associated information other than that corresponding to the replayed portion, when a predetermined time elapses after the piece of associated information other than that corresponding to the replayed portion is selected, the output controlling unit is configured to automatically switch displayed associated information, after the predetermined time has elapsed, from the piece of associated information other than that corresponding to the replayed portion to the piece of associated information corresponding to the replayed portion of the content data of the time after the predetermined time has elapsed, and the content data is audio data and the associated information is lyrics, chord names representing chord sounds, musical scales, musical symbols used in a score and/or symbols representing who is to sing parts in music.