A retaining device includes a top clamping seat having arms divergently extending out of the top clamping seat and each arm provided with a claw adjustably connected to the arm, a bottom seat having linkages pivotally extending upward to pivotally connect to mediate portions of the arms, and an adjusting ring adapted to be threadingly connected to the drum stand to abut a side face of the bottom seat to cause the bottom seat to move. Movement of the bottom seat is able to initiate movement of the top clamping seat and thus the claws are able to clamp a drum seated on the drum stand and the adjustability of the claws relative to the arms allows the retaining device to clamp drums of different sizes.