In a disc drive apparatus, provided in the front face thereof is a changeover switch for changing over settings between a master and a slave in working of disc drive apparatus. Changeover switch is electrically connected to a substrate in the interior thereof by a cable. A cover is provided near the front face of changeover switch so as to cover it. A prescribed lock mechanism is provided to cover so that cover is neither opened erroneously nor changed over in operation of disc drive apparatus. A previous locking of lock mechanism is cancelled in a state where disc drive apparatus in out of operation, thereby enabling changeover between settings of a master and a slave in working. With such a construction adopted, a disc drive apparatus is obtained in which change over is easily performed between settings of a master and a slave in working thereof and a set state thereof is immediately confirmed.