According to one embodiment, the Web pages that match a user's designated collection condition are collected from a plurality of Web sites. The collected Web pages are divided into a plurality of clusters, based on URL information of the Web pages. A date expression is extracted from Web pages included in each of the clusters. A typical date expression form is determined for each of the clusters, based on the extracted date expression. The Web pages included in each of the clusters are divided into a plurality of items, based on the date expression form. The items are sorted for each of the clusters in order of time, based on date expressions corresponding to the items. Time-series data is generated for each of the clusters by sorting the items.