A remote monitoring system comprising a data collecting device and a monitoring device, the data collecting device comprising: an equipment communicator adapted to accomplish data communication with facility equipment (10, 11) that constitutes a facility equipment control system; a first remote communicator adapted to accomplish data communication with the monitoring device; an operation data collector adapted to collect operation data indicating the operation status of the facility equipment (10, 11); an operation data storage adapted to store the operation data collected by the operation data collector; and an operation data transmitter adapted to transmit operation data read from the operation data storage to the monitoring device, the monitoring device comprising: a second remote communicator adapted to accomplish data communication with the data collecting device; and an operation receiver adapted to receive operation input from a user, wherein: the operation data is numerical data, the operation data transmitter is adapted to group multiple items of operation data read from the operation data storage according to identification information of the facility equipment (10, 11) and a type of the operation data, extract a difference in the operation data in a chronological manner for each group to thereby generate compressed data with a prescribed format, and transmit the generated compressed data to the monitoring device, the monitoring device further comprises: a user data storage adapted to store a user data table in which types of operation data disclosable to each user are defined; an operation data requestor adapted to acquire types of operation data selectable by a user based on the user data table when operation input that requests monitoring of operation data is accomplished by the user, and to cause the user to select a desired type of operation data from the acquired types of operation data; and an operation data display that is adapted to decompress the compressed data received from the data collecting device, restore the one or multiple items of operation data, and display contents of the restored one or multiple items of operation data on a display device. an equipment communicator adapted to accomplish data communication with facility equipment (10, 11) that constitutes a facility equipment control system; a first remote communicator adapted to accomplish data communication with the monitoring device; an operation data collector adapted to collect operation data indicating the operation status of the facility equipment (10, 11); an operation data storage adapted to store the operation data collected by the operation data collector; and an operation data transmitter adapted to transmit operation data read from the operation data storage to the monitoring device, a second remote communicator adapted to accomplish data communication with the data collecting device; and an operation receiver adapted to receive operation input from a user, wherein: the operation data is numerical data, the operation data transmitter is adapted to group multiple items of operation data read from the operation data storage according to identification information of the facility equipment (10, 11) and a type of the operation data, extract a difference in the operation data in a chronological manner for each group to thereby generate compressed data with a prescribed format, and transmit the generated compressed data to the monitoring device, the operation data is numerical data, the operation data transmitter is adapted to group multiple items of operation data read from the operation data storage according to identification information of the facility equipment (10, 11) and a type of the operation data, extract a difference in the operation data in a chronological manner for each group to thereby generate compressed data with a prescribed format, and transmit the generated compressed data to the monitoring device, the monitoring device further comprises: a user data storage adapted to store a user data table in which types of operation data disclosable to each user are defined; an operation data requestor adapted to acquire types of operation data selectable by a user based on the user data table when operation input that requests monitoring of operation data is accomplished by the user, and to cause the user to select a desired type of operation data from the acquired types of operation data; and a user data storage adapted to store a user data table in which types of operation data disclosable to each user are defined; an operation data requestor adapted to acquire types of operation data selectable by a user based on the user data table when operation input that requests monitoring of operation data is accomplished by the user, and to cause the user to select a desired type of operation data from the acquired types of operation data; and