A weak magnetic force magnetic separator, including: a belt conveyor conveying separation target particles; and a suspended magnet unit provided at a distance above the belt conveyor and configured to magnetically attract, with a uniform, weak magnetic force, the separation target particles conveyed over a belt. With a length of the magnet unit in its longer direction being greater than a belt width of the belt, and with the magnet unit placed such that its longer direction is aligned with the belt width direction and its both ends overhang the belt width, and such that a distance from the surface of the belt is constant across its longer direction, magnetic flux density variations in the belt width direction over the belt surface facing the magnet unit are 10% or less within a weak magnetic force range of from over 0 to 700 gauss.