A storage system including a storage device (1) which includes: media (50) for storing data from a host computer (2); a medium controller (14) for controlling the media; a plurality of channel controllers (11) for connecting to the host computer (2) through a channel; and a cache memory (13) for temporarily storing data from the host computer (2), wherein the media (50) have a restriction on a number of writing times. The storage device (1) includes a bus (123) for directly transferring data from the medium controller (14) to the channel controller (11).