The detent force in permanent magnet linear synchronous motor (PMLSM) is caused by the attraction between the permanent magnet (PM) and the iron core without input current. It can be divided into two components: the slot effect and the end effect. This paper proposes a novel technique to reduce the end effect of detent force using auxiliary poles. To investigate the auxiliary poles design criteria, we analyze the characteristics of the detent force according to the height, length, and position of the auxiliary poles by using the 2-D finite-element method (FEM). The numerical calculations and the experimental results prove that this proposed technique has a good effect on the reduction of the end effect of detent force.