This paper varies load conditions in a single-phase induction motor and deals with consequent effects on the electromagnetic characteristics in terms of a balanced and unbalanced operation. Based on a balanced-load condition, the magnetic field, electromagnetic losses, magnetic torque are quantified by the time-stepping finite element method at six different loads. The spatial distribution of the air-gap magnetic field are investigated to characterize the existence between the load variation and unbalanced operation. The components of electromagnetic losses are analyzed in terms of main parameters degrading the operating efficiency according to the load variation. The result can show the importance of building the magnetic balance for a high performance, and the design guideline for SPIMs running at multiple operating points is discussed.