A storage system includes: an access path management unit managing a state of each access path for each logical disk; an I/O speed calculation unit storing, for each of the access paths, a data size and required time obtained when an I/O is executed, and calculates an I/O speed for every calculation cycle; a path candidate selection unit selecting an access path in the available state as an I/O use candidate; and a path candidate exclusion unit which excludes access paths of which speed is slow from the candidates, using a highest speed value among the speed values of the access paths selected as candidates, and the access path management unit sequentially changes the states of the access paths, out of the remaining candidates, to the I/O use states, in order of the I/O speed from the fastest until the number of access paths reaches the maximum number of paths.