A method for managing data, comprising: receiving data about information collected by a sensor, in which at least a part of the data is encrypted; and performing an analysis in a state where both non-encrypted section and encrypted section of the data are not decrypted.Also, a method for managing data encryption, comprising: allowing a sensor or an intermediate network device to encrypt at least a part of data about collected information; allowing the sensor or the intermediate network device to transmit the at least partially encrypted data; allowing a data management apparatus to receive the at least partially encrypted transmitted data; allowing the data management apparatus to store the at least partially encrypted received data; and allowing the data management apparatus to perform an analysis in a state where both non-encrypted section and encrypted section of the at least partially encrypted data are not decrypted.