A terminal status monitoring apparatus connected to a terminal at an optical subscriber side in an optical network is provided. A signal transferring unit transfers a downlink optical signal to the terminal and receives, as a reflected optical signal, the downlink optical signal which is reflected at the terminal. A signal receiving unit measures an intensity of the reflected optical signal. A signal processing unit determines a connection status of a terminal device at the terminal by comparing an intensity of the downlink optical signal with the intensity of the reflected optical signal. A signal output unit outputs the connection status.