A tubular system includes a tubular apparatus 100 including a flexible inserting section and a physical quantity detector 111, a physical quantity detector signal processing box 300 to process a signal from the physical quantity detector, and a detachable connection cable 200 to connect the tubular apparatus 100 with the physical quantity detector signal processing box300. The connection cable 200 includes a light source 211 to supply light to an optical waveguide of the physical quantity detector 111, a photodetector 214 to detect light modulated by the physical quantity detector 111, a light entrance/exit section to supply or receive an optical signal to or from the physical quantity detector 111, and an electrical input/output section to supply or receive an electrical signal to or from the physical quantity detector signal processing box.
