A centralized management unit for facility equipment, which is adapted to be connected to at least one piece of facility equipment to be managed, which is adapted to obtain management data from the at least one piece of facility equipment, which is adapted to be connected to a connection intermediating device for connecting the centralized management unit to a monitoring terminal and which is adapted to transmit the management data to the monitoring terminal via the connection intermediating device, and which comprises: an input-side interface adapted to be connected to said facility equipment to be managed; an output-side interface for outputting said management data of said facility equipment and for receiving information transmitted from said monitoring terminal; a storage section for storing a control program of said facility equipment; and an arithmetic processing section for controlling said facility equipment in accordance with an instruction of said control program; wherein said storage section stores a first transmission program corresponding to said input-side interface and a second transmission program corresponding to an interface of said connection intermediating device; wherein said arithmetic processing section is adapted to obtain said management data from said facility equipment via said input-side interface in accordance with an instruction of said first transmission program and to output said management data to said output-side interface in a mode corresponding to the interface of said connection intermediating device in accordance with the instruction of said second transmission program, wherein said arithmetic processing section is adapted to store a program in an area for storing said second transmission program, on the basis of information received from said output-side interface on said program to be stored in said area where said second transmission program is stored, wherein said centralized management unit further comprises path switching means for branching output destinations of said output-side interface, said path switching means being adapted to output said management data of said facility equipment from one branch path; and wherein a program setting device for setting information related to a program to be stored in the area where said second transmission program is stored is connected to the other branch path. an input-side interface adapted to be connected to said facility equipment to be managed; an output-side interface for outputting said management data of said facility equipment and for receiving information transmitted from said monitoring terminal; a storage section for storing a control program of said facility equipment; and an arithmetic processing section for controlling said facility equipment in accordance with an instruction of said control program; wherein said storage section stores a first transmission program corresponding to said input-side interface and a second transmission program corresponding to an interface of said connection intermediating device; wherein said arithmetic processing section is adapted to obtain said management data from said facility equipment via said input-side interface in accordance with an instruction of said first transmission program and to output said management data to said output-side interface in a mode corresponding to the interface of said connection intermediating device in accordance with the instruction of said second transmission program, wherein said arithmetic processing section is adapted to store a program in an area for storing said second transmission program, on the basis of information received from said output-side interface on said program to be stored in said area where said second transmission program is stored, wherein said centralized management unit further comprises path switching means for branching output destinations of said output-side interface, said path switching means being adapted to output said management data of said facility equipment from one branch path; and wherein a program setting device for setting information related to a program to be stored in the area where said second transmission program is stored is connected to the other branch path.