An optical fiber sensing system according to the present disclosure includes a sensing optical fiber (20), a medium (10) with which the sensing optical fiber (20) is integrated, and which is arranged in a monitoring target (50), an optical fiber detection unit (30) which is connected to the sensing optical fiber (20) integrated with the medium (10), the optical fiber detection unit (30) is configured to receive an optical signal from the sensing optical fiber (20), and detect a pattern according to a state of the monitoring target (50), contained in the optical signal, and a state detection unit (40) configured to detect a state of the monitoring target (50), based on the pattern contained in the optical signal.