1. A network monitor and control apparatus for controlling the monitoring of a network, comprising: an error monitor including an error information gatherer using a processor 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, wherein N is a positive integer, 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, and wherein if a fresh monitor target apparatus is added, an apparatus type identifying unit acquires from the fresh monitor target apparatus an apparatus type identifier for identifying the apparatus type of the fresh monitor target apparatus, and determines whether the fresh monitor target apparatus has been registered as an apparatus type and as a monitor target.