To provide a magnet unit that can be miniaturized, while maintaining a desired magnetic flux density.

The magnet unit 100 includes a magnet group 110 and a fastening member 120. In the magnet group, holes 111h, 116h extended from an end face which respective magnets 111, 116 oppose are formed, and first screws 112, 117 are formed at least at one portion of an inner peripheral surface of the holes 111h, 116h in at least one of the magnets 111, 116. The fastening member includes a columnar cylinder section insertable into the holes 111h, 116h, forms a second screw 121 threadedly engaged with the first screws 112, 117 in at least one portion of an outer peripheral surface of the cylinder section, and is made of a non-magnetic material.