Elliptic curve cryptosystems (ECCs) are cryptographic schemes based on the discrete logarithm problem on an elliptic curve. ECCs are that it can achieve the necessary security with a short key size compared to other cryptographic schemes. Therefore, it is expected to be used in IoT devices that cannot use large memory, but more compact and efficient cryptography is needed to further improve performance. Scalar multiplication, the main operation in ECCs, must be made more efficient while providing side-channel attack (SCA) resistance. Elliptic curve GLS254 defined on a finite field of characteristic 2 has an endomorphism that can be efficiently computed, contributing to efficient scalar multiplication. A secure scalar multiplication using (x, s) coordinates which can define an addition formula with no exception points has been proposed for GLS254. In this study, we propose a secure and faster method for GLS254 by focusing on the addition formulae and its coordinate system. The result is a method that is faster than the existing scalar multiplication algorithm by 7.1%.