Disclosed herein is a data management apparatus including, a management-data storage unit for storing management-object data, a management-data verification-value storage unit for storing a top value placed on the top of an n-branch data-management tree as a management-data verification value where n is an integer equal to or greater than two, and a data verification process unit for carrying out a process to verify validity of the management-object data on the basis of the management-data verification value, wherein, the n-branch data-management tree includes the management-object data located on a hierarchical layer at the lowest level of the n-branch data-management tree and data located on any specific hierarchical layer at a higher level of the n-branch data-management tree as a result of computation by using a irreversible function based on other data located on another hierarchical layer at a level directly subordinate to the specific hierarchical layer, and the top value is a result of computation by using the irreversible function based on data located on a hierarchical layer at the highest level of the n-branch data-management tree.