1. An image tagging device comprising: a processor, and a storage that stores instructions that, when executed by the processor, cause the processor to execute: generating a first image by changing a first region image corresponding to a first object related to privacy information in a master image stored in a first memory and thereby removing the privacy information included in the master image; generating an operation request image by changing a second region image corresponding to a second object that is not to be tagged in the first image; distributing the generated operation request image to a tagging operation terminal device over a network; receiving image tag information, as a response to the distributed operation request image, from the tagging operation terminal device over the network; and generating a tagged image on the basis of the master image and the image tag information, wherein the operation request image with removed privacy information and removed second object information is distributed to the tagging operation terminal device to increase privacy of information being transmitted over the network, and to increase efficiency of the tagging operation terminal device due to reduced information to be processed in a tagging operation.