The aim of this paper is to investigate the evolutionary optimization technique which can be applied in the design of electromagnetic devices, in particular case Of the induction heaters in order to automate some parts of the designing process. For electromagnetic problems, the optimal design is usually a multiobjective task with different specifications, often in conflict among them, have to be pursued with several design degrees of freedom, which are the design parameters. Also, the device parameters have to satisfy some technological and physical constraints. Therefore it is necessary to use a multiobjective optimization strategy