This paper reports the methodological approaches to detent force reduction in the steel-cored Permanent Magnet Linear Synchronous Motor (PMLSM). For the detail investigations and overviews on the detent force, analytic solutions considering the various reluctances in the air-gap were obtained using the Space Harmonic Method. The validity of this method was confirmed by comparing the results of the FEM. With the thorough investigation of the causes of detent force, the reduction methods that minimize the force ripple under the consideration of manufacturing feasibility are introduced, and certified by experimentation of the test machine.