A state transition of a player operation is explicitly defined to facilitate the production of interactive contents. As a player model for reproducing a disk, a model including a player 300 for reproducing a stream, a platform 301 providing an interface between the player 300 and a hardware, and a script player 302 for realizing a scenario intended by a content producer is conceived. The states of the player 300 are defined by four states defined by combinations of two states as to whether the play list reproduction is performed or not and two states as to whether the command 311 is accepted or not. The state transition of the player 300 among the four states is generated by a method 313 from the script layer 302, but not by the player 300 itself or the command 311. The states of the player 300 are small in number, and the conditions for state transition are definite. Therefore, the interactive contents can be easily produced and mounted on devices.