A method of merging data objects, including folders and opened information items, at the same level and an apparatus performing the method are provided. The data object merging method includes receiving a user command to merge two data objects; and merging the contents of the two data objects according to the input user command. According to the method and apparatus, folders can be merged at the same level and image data or text data can be input as individual objects and then, when necessary, the information items can be easily merged such that file management can be performed conveniently.