This paper deals with experimental works and analysis for influence of stator slot number on performance of interior PM (IPM) motor. First, for a conventional 6-pole IPM rotor, stators with 18, 27 and 36 slots satisfied with same required and restricted conditions are designed. And then, performances and parameters of each IPM motor such as cogging torque, torque ripple, d- and q- axis inductance, total harmonic distortion (THD) of back-emf, etc. are investigated using 2-d finite element analyses (FEA). Finally, test results such as d- and q- axis inductance, back-emf and efficiency measurements are given to confirm analysis results. It is concluded from the results obtained by this work that the influence of stator slot number on IPM motor behavior is very significant.