The present invention relates to a composition for detecting an epidermal cell growth factor receptor gene mutation and to a kit comprising the composition and, more specifically, to a primer and probe set composition for detecting an epidermal cell growth factor gene mutation, and to a kit for detecting an EGFR gene mutation, comprising the composition. A method according to the present invention can not only predict and diagnose responsiveness to a therapeutic agent for the prognosis of a cancer patient, but also predict a cancer metastasis or relapse Thus, the method can be useful for the purposes of determining the need to administer an anticancer therapeutic agent and guiding the direction of future treatment, and for monitoring a cancer metastasis or relapse.