An image processing apparatus comprises a first storage area that stores in itself original data to be copied; a copier that copies the original data to a second storage area that is shared and allowed to be accessed by a plurality of users belonging to one same group, by storing reference information pointing to the original data stored in the first storage area, in the second storage area; a judger that judges whether or not all of access judgment target users who are the group users sharing the second storage area or preliminarily specified users, make access to the reference information stored by the copier in the second storage area; and a controller that suspends execution of an instruction given to change the original data for the access judgment target users so that the original data could be provided to all of them, if the judger judges that only some of the access judgment target users has made access to the reference information when the instruction to change the original data is given, and then, cancels the suspension after the original data is provided to all of the access judgment target users.