the present invention relates to an apparatus for providing storage security of a cloud server in a cloud computing environment in which a client terminal is connected to the cloud server over a communication network . the apparatus includes a monitor configured to monitor which file data is requested for writing or transferring among file data stored in a storage of the cloud server and a controller configured to detect whether the file data monitored by the monitor is the file data belonging to a predetermined secure space and to block or hold the writing or transfer for the file data when the detected file data belongs to the predetermined secure space .