It still has some restrictions to collect a specialized information with only the function of existing web robot which collect an enormous of data by circulating through the internet. Therefore, in this paper the functions of the current web robot and its application areas are analyzed and the limitations of collecting a specialized information are found out. Also we define what functions are necessary for a web robot in order to collect a specialized information. Then the designed structure is described. There are two critical functions which are applied to web robot. One is a genre-based categorization that classifies the text by the type, and the other is a content-based categorization by the subject. Most of all, genre-based categorization is used as fundamental feature which enables web robot to collect the aimed documents efficiently.