Main problems of accelerator-driver design for ADS are considered. Accelerator-driver should meet additional requirements in comparison with accelerators for other purposes: - high neutron production rate; - higher reliability; - continuous operation for more than 5000 hours; - possibility of accelerator parameters adjustment to regulate ADS power level. Different types of accelerators were analyzed taking into account the mentioned features and the fact that the most prospective way of ADS application nowadays is transmutation. It's shown that the most preferable accelerator type is proton linac. Also it's marked that for demonstration facilities accelerators with lower requirements and correspondingly cost can be used.