A tubular system includes a tubular apparatus including a flexible inserting section and a physical quantity detector, a physical quantity detector signal processing box to process a signal from the physical quantity detector, and a detachable connection cable to connect the tubular apparatus with the physical quantity detector signal processing box. The physical quantity detector includes an optical waveguide arranged in the inserting section. The connection cable includes a light source to supply light to the optical waveguide, a photodetector to detect light modulated by the physical quantity detector, a light entrance/exit section to supply or receive an optical signal to or from the physical quantity detector, and an electrical input/output section to supply or receive an electrical signal to or from the physical quantity detector signal processing box.
