US Patent 9076010 Anonymization device

The present invention enables comparison of the number of data items between groups. The anonymization device according to the present invention refers to a user information storage unit storing data items including user information, detects a singularity group that does not satisfy a predetermined anonymity metrics when the data items corresponding to a plurality of users are grouped based on the user information, selects an acquired data item from each group based on a predetermined rule corresponding to the anonymity metrics, such that all groups satisfy the anonymity metrics when a data item is acquired from each of the groups other than the singularity group and the user information is generalized into the same value together with a data item of the singularity group, generates an anonymized data item by generalizing the user information of the data item of the singularity group and the acquired data items into the same value, and stores the generated anonymized data items in an anonymized user information storage unit, together with a data item of each group other than the singularity group, with this data item being other than the acquired data items.