An image processing apparatus includes a storage unit for storing user information correlating user identification information and acknowledger information in advance; an image file acquiring unit for acquiring the image file; and a control unit for controlling a writing process in a detachable storage medium. The control unit includes a registration processing unit for correlating the user identification information and authentication information contained in an acknowledgement notice, and for registering the user identification information and the authentication information as acknowledgement information in the storage unit. The control unit further includes a determining unit for determining whether the user identification information and the authentication information received through an input unit are registered in the acknowledgement information, and for allowing the image file stored in the storage unit to be written in the detachable storage medium when the authentication notice is authenticated.