An adjustable hanging apparatus for blind valances is provided. The hanging apparatus includes a hanging device and a mounting device. The hanging device has a hook, which can be slidably hooked over a headrail. In addition, a base of the hanging device has an opening. The opening is disposed with two resilient mounting plates, and each mounting plate has a plurality of troughs. A neck portion is formed therebetween the mounting plates. The mounting device has a joint portion, which can engage with the valance. Also, a jam portion passes through the neck portion and mounted therein. Positioning flanges can be engaged with the troughs of the mounting plates so as to limit the vertical movement of the mounting device, and the mounting device can be inserted through the opening in the vertical direction of any positions to adjust the valance to desired positions.