A data sharing system comprising: a plurality of data providing servers; a common database; and a management server, wherein each of the plurality of data providing servers includes: a sensitive data acquisition unit configured to acquire sensitive data including attribute values of each of attribute items; a key management unit configured to manage an encryption key and a decryption key; and an encryption unit configured to encrypt at least a part of the attribute values of the sensitive data by a predetermined encryption scheme based on the encryption key, the common database is configured to store an integrated data obtained by integrating the sensitive data encrypted in the plurality of data providing servers based on an identifier which is included in the sensitive data as one of the attribute items, the management server includes: a reception unit configured to receive a first processing request of a data processing processed to the integrated data stored in the common database; an execution unit configured to execute the data processing; and a decryption request unit configured to transmit a second processing request of a decryption processing to the plurality of data providing servers for requesting the plurality of data providing servers to decrypt an execution result of the data processing, each of the plurality of data providing servers further includes a decryption unit configured to decrypt the execution result based on the decryption key in accordance with the second processing request of the decryption processing transmitted from the decryption request unit of the management server, wherein the common database stores a table including the attribute items as columns, the data processing includes a retrieval processing and/or a statistical processing targeted at least a part of the attribute items of the integrated data, and the decryption request unit requests one of the plurality of data providing servers to decrypt the execution result by a decryption key managed by the one of the plurality of data providing servers, the one of the plurality of data providing servers providing the sensitive data including the attribute items to which the data processing is executed. a plurality of data providing servers; a common database; and a management server, wherein each of the plurality of data providing servers includes: a sensitive data acquisition unit configured to acquire sensitive data including attribute values of each of attribute items; a key management unit configured to manage an encryption key and a decryption key; and an encryption unit configured to encrypt at least a part of the attribute values of the sensitive data by a predetermined encryption scheme based on the encryption key, a sensitive data acquisition unit configured to acquire sensitive data including attribute values of each of attribute items; a key management unit configured to manage an encryption key and a decryption key; and an encryption unit configured to encrypt at least a part of the attribute values of the sensitive data by a predetermined encryption scheme based on the encryption key, the common database is configured to store an integrated data obtained by integrating the sensitive data encrypted in the plurality of data providing servers based on an identifier which is included in the sensitive data as one of the attribute items, the management server includes: a reception unit configured to receive a first processing request of a data processing processed to the integrated data stored in the common database; an execution unit configured to execute the data processing; and a decryption request unit configured to transmit a second processing request of a decryption processing to the plurality of data providing servers for requesting the plurality of data providing servers to decrypt an execution result of the data processing, a reception unit configured to receive a first processing request of a data processing processed to the integrated data stored in the common database; an execution unit configured to execute the data processing; and a decryption request unit configured to transmit a second processing request of a decryption processing to the plurality of data providing servers for requesting the plurality of data providing servers to decrypt an execution result of the data processing, each of the plurality of data providing servers further includes a decryption unit configured to decrypt the execution result based on the decryption key in accordance with the second processing request of the decryption processing transmitted from the decryption request unit of the management server, wherein the common database stores a table including the attribute items as columns, the data processing includes a retrieval processing and/or a statistical processing targeted at least a part of the attribute items of the integrated data, and the decryption request unit requests one of the plurality of data providing servers to decrypt the execution result by a decryption key managed by the one of the plurality of data providing servers, the one of the plurality of data providing servers providing the sensitive data including the attribute items to which the data processing is executed.