A multi-core system 1 according to the present invention includes a plurality of OSs: OS[1] 110 and OS[2] 120 set as a main system and a standby system for a sound reproducing function. The standby-system OS[1] 110 sets a timer 17 according to a DMA transfer completion interruption request to detect a failure of the main-system OS[2] 120 according to detection of timeout by the timer 17. Upon detection of a failure of the main-system OS[2] 120, the standby-system OS[1] 110 is switched as the main-system OS[2] 120 to operate a device driver 114 on a side of the standby-system OS[1] 110, thereby continuously executing audio mixing processing of audio data and DMA transfer request processing.