In this paper, we propose efficient masking methods for ARIA and AES. In general, a masked S-box (MS) block can be constructed in different ways depending on the implementation platform, such as hardware and software. However, the other components of ARIA and AES have less impact on the implementation cost. We first propose an efficient masking structure by minimizing the number of mask corrections under the assumption that we have an MS block. Second, to make a secure and efficient MS block for ARIA and AES, we propose novel methods to solve the table size problem for the MS block in a software implementation and to reduce the cost of a masked inversion which is the main part of the MS block in the hardware implementation.