A flywheel-type variable resistance generating device for an exercising apparatus includes two actuating arms disposed outboard of a flywheel, a pulling cord having two anchoring ends coupled with a tightening-force adjusting member and a lever, and two pull-activating members connected to the pulling cord so as to move the actuating arms. The actuating arms are movable among a starting position where they are disengaged from the flywheel, an adjusted position where they are partially engaged with the flywheel, and a braking position where they are fully engaged with the flywheel. When the lever is operated to move one anchoring end with a braking force, the other anchoring end of the pulling cord is pulled back to its initial locus to move the actuating arms to the starting position.