A multimedia processing device implements a script having a data structure that is formed of a drawing information describing portion where media data is chronologically described, and a user navigation information describing portion where correspondence between events and actions and implementation conditions are chronologically described. The multimedia processing device implements this script, and thereby, media data is chronologically reproduced, and at the same time, a user interface showing operations that can be chronologically carried out is outputted. Then, a predetermined process, such as an insertion of media data, can be implemented by carrying out the operations following the user interface according to predetermined timing.