To enable only a necessary part to be distributed to a terminal of a computer maintenance service center by storing an added and updated document as differential data, every time a maintenance related document is added and updated, and transmitting it.

From a control center system 1, electronic information on a maintenance related manual about user systems 4A-4X are distributed to service centers 3A-3B by way of a public line 2 or by being stored in a storage medium and inputted to a service center system 3. Original data are stored in a storage device of a service center system 1 and when a change is caused to the manual, with regard to the change, only the part which is different from the previous ode is communicated and distributed as difference data. In the service center system 3, the latest manual considering the original data and the whole difference data communicated and distributed is edited and the edited manual is stored in an online terminal 5. A maintainer utilizes the manual and carries out a maintenance work.