1. A network monitor and control apparatus for controlling the monitoring of a network, comprising: an error monitor including an error information gatherer for gathering error information of a monitor target apparatus; and a monitor result notifier for notifying of monitor results, wherein if there are N types of monitor target functions, the error monitor includes N error information gatherers for the respective N types of monitor target functions (N=1, 2, 3,. .. ) and wherein each of the N error information gatherers gathers the error information from one of an existing monitor target apparatus and a newly added monitor target apparatus on a per monitor target function basis.