A BD-ROM playback apparatus simultaneously executes reproduction of a title including an AVClip and executes an application. The BD-ROM playback apparatus includes a BD-J module (35) executing an application, a playback control engine (32) for playing the AVClip belonging to one title, and a module manager (34) for controlling branching between a plurality of titles. The title includes a data management table. The data management table indicates an application read priority level for each title. The BD-J module (35) includes a java virtual machine (38), a local memory (29), and an application manager (36) for loading the application to the local memory (29). The application manager (36) reads in the application into the local memory (29) according to the read priority level of each application and the memory size of the local memory (29).