In this paper, the general research on the analysis of the vibration due to magnetic exciting force in the small brushless DC(BLDC) motor, which is used in the Digital Versatile Disk(DVD) ROM driving system, is performed. The first part of the study is the analysis of the magnetic exciting force in the air gap region. As a verification of the exciting force by numerical analysis, the magnetic exciting force distribution in the air gap region is computed by using Reluctance Network Method(RNM). In addition, the effect of the eccentricity on the magnetic exciting force is discussed. The other part of the research is the structural analysis of the rotor structure of the BLDC motor. The matural mode analysis of the rotor structure is performed, and the vibration response due to magnetic exciting force is found. As a result of the procedures, the basic estimation of the effect of the magnetic exciting force on the vibration of BLDC motor is suggested.