Abstract: Disclosed are: a method for detecting a target biomolecule in a biological sample, in which the method can be rapidly and inexpensively performed on site to diagnose diseases such as infectious diseases; an FO-LSPR optical fiber sensor which can be used therein; and a disposable sensor cartridge having the sensor mounted. The disposal sensor cartridge of the present invention can he used in the rapid detection of a target biomolecule, by mounting an optical fiber sensor and then connecting FO-LSPR equipment thereto. When an FO-LSPR molecular diagnostic system using the optical fiber sensor cartridge of the present invention is combined with a CRISPR-Cas system, target biomolecules can be detected accurately and conveniently without nucleic acid amplification.