Due to the channel achieving property, the polar code has become one of the most favourable error-correcting codes. As the polar code achieves the property asymptotically, however, it should be long enough to have a good error-correcting performance. Although the previous fully parallel encoder is intuitive and easy to implement, it is not suitable for long polar codes because of the huge hardware complexity required. In this brief, we analyse the encoding process in the viewpoint of very-large-scale integration implementation and propose a new efficient encoder architecture that is adequate for long polar codes and effective in alleviating the hardware complexity. As the proposed encoder allows high-throughput encoding with small hardware complexity, it can be systematically applied to the design of any polar code and to any level of parallelism.