A waistband tightening device has a generally horizontal crank arm with a first and second leg at one end extending vertically therefrom in parallel spaced relation defining a vertical slot therebetween, and a fastener element at the opposed end disposed in outwardly spaced relation to the legs. The device is installed downward onto the waistband with the legs straddling the waistband, and the crank arm and fastener element are rotated in a clockwise or counterclockwise direction with the slot being the center of rotation such that the waistband becomes looped partially around the first and second legs and upon further rotation becomes wound around both of the legs to reduce the circumference of the waistband and thereafter the fastener element is engaged on an inner or outer facing surface of the waistband to prevent unwinding and maintain the waistband in a tightened condition.