Recently, it seems to be interested in the conversational agent as an effective and familiar information provider. Most of conversational agents reply to user's queries based on static answers constructed in advance. Therefore, it cannot respond with flexible answers adjusted to the user, and the stiffness shrinks the usability of conversational agents. In this paper, we propose a method using genetic programming to generate answers adaptive to users. In order to construct answers, Korean grammar structures are defined by BNF (Backus Naur Form), and it generates various grammar structures utilizing genetic programming (GP). We have applied the proposed method to the agent introducing a fashion web site, and certified that it responds more flexibly to user's queries.