A decoding method in a mobile communication system using a non-binary LDPC code according to various embodiments of the present disclosure includes: selecting a message value having the highest reliability from each column and each row of an input vector message; generating a configuration set using the message value selected for each column and a GF element corresponding to the message value; and generating a check node output message using the generated configuration set and an extra output message value. According to various embodiments of the present disclosure, a decoding time period is reduced.