This study proposes a damping control strategy for high-speed operation of a wave energy converter (WEC). The control strategy of WEC is based on the heave-motion (up/down motion) mechanism of buoy. The applied WEC system extracts power through damping control of the permanent magnet linear generator, which is directly connected to the buoy. This study first analyzed the mechanical dynamics of a WEC system. Further, a damping control method that could improve the extracted power for a wide speed range is examined. The results showed that the operating region could be expanded and the power extraction could be maximized using only the proposed software implementation, without requiring additional hardware. The validity and benefits of the proposed control algorithm were experimentally verified using a down-scaled WEC model.