A magnet yoke of a linear motor includes a plurality of recesses set in equidistance in a side surface of the magnet yoke and defining a plurality of peaks and valleys arranged alternately and a plurality of permanent magnets aligned abreast in equidistance in an opposite side surface of the magnet yoke so that an interval is defined between two adjacent permanent magnets and has a center aligned with a center of a corresponding peak and valley. Two adjacent permanent magnets form a magnet unit for generating a magnetic flux distribution. An empty section formed in each of the valleys is twice as wide as an interval between two adjacent permanent magnets, and is located in a middle of the two permanent magnets so as to make a moderate magnetic flux distribution.