A DMA controller controls DMA transfer in an information processing system. Input and output devices are a transfer source or a transfer destination in DMA transfer and request DMA transfer. A DMAC activating unit is provided with an event monitoring unit and an event register. The event register registers an event subject to monitoring. The event monitoring unit detects an event generated in the input and output devices and determines whether the detected event matches an event registered in the event register. If it is determined that the events match, the event monitoring unit activates the DMA controller.