A management device performs any one of first processing where an image forming apparatus whose operation set as a mode transfer operation is the same as an unauthorized operation detecting image forming apparatus is made to change the presently set mode transfer operation, second processing where image forming apparatuses which belong to a group that the unauthorized operation detecting image forming apparatus belongs to are made to change the presently set mode transfer operation and third processing where the image forming apparatuses which belong to the group that the unauthorized operation detecting image forming apparatus belongs to are prevented from being transferred to a maintenance mode.