Ocean wave could convert the resource energy more than half of its potential capacity often over time, compared with wind or solar system, which is less than half of its capacity resource. However, the challenge rises on designing an ocean wave-capturing device that can achieve optimum efficiency. This paper addressed several topics including the overview of existing technology of wave energy converter with emphasis on wave-activated body category, current principle of energy harnessing, types of generators utilised to harness the wave energy and the current technologies of power electronics implemented to ocean wave devices. Wave energy converters (WEC) that are commercialised, under testing and still in prototype stage are all listed and divided into two different categories, namely, submerged and floating on the sea. The results reveal that, compared with submerged WECs, the floating WECs gain more attention for development. The key factor in choosing a float on device is to consider the fabrication cost, environmental impact especially for marine life, design and maintenance issue, installation site and the selection of power take-off system.