A device controller that improves transfer speed when the total data amount to be transferred exceeds a predetermined amount, without requiring a special configuration in the device.The device controller includes a cache memory that caches data received from an application software or device driver and data received from a target device, and a control unit that transfers the data cached in the cache memory to the target device and the application software or device driver. The control unit receives a read or write request from upstream and caches the transfer data in the cache memory. During writing, the data received from upstream is cached, and once a certain amount of data has been collected, it is sent downstream. During reading, a certain amount of data is collectively read out from downstream and sent upstream.