1. A data integration apparatus collecting and integrating data in a plurality of information sources managed in different systems, comprising: a data collecting unit that directly collects, from each of the information sources, the data as a physical model of each of the information sources; a data integration engine that converts at least a data configuration or a data value such that the data collected by the data collecting unit are formed into a logical model preliminarily defined for each utilization-side application utilizing the data; and a data providing unit that provides the data converted by the data integration engine to the utilization-side application.