A gear cam mounting device in a dual-hinge device for a portable terminal is provided, in which first and second hinge shafts provide first and second parallel hinge axes, respectively, first and second gear cams are fixed around the first and second hinge shafts, in engagement with each other, and first and second locking units penetrate respectively through the first and second gear cams in a direction that is perpendicular to the first and second hinge axes, for locking the first and second gear cams to surround the first and second hinge shafts.