The present invention is directed to enable a monitoring apparatus to reliably obtain information of an event which occurs in an apparatus to be monitored in a monitoring system employing a connectionless communication method. An apparatus to be monitored comprises: a first transmitting unit for transmitting first information as event information related to an event in the apparatus to be monitored to a monitoring apparatus by a connectionless communication method; and a second transmitting unit for transmitting second information as the event information to the monitoring apparatus by a communication method different from the connectionless communication method. The monitoring apparatus comprises: a first receiving unit for receiving the first information transmitted from the first transmitting unit; and a second receiving unit for receiving the second information transmitted from the second transmitting unit.