Fiber optic SERS probe enables remote biomolecule sensing through an optical fiber with high repeatability by utilizing the whole plasmonic nanostructure on the fiber tip as a SERS-active substrate with advantages of an optical fiber such as minimal invasiveness, flexibility, and biocompatibility. These remarkable characteristics of fiber optic SERS probe are comparable to labeled metal nanoparticles that have disadvantages of toxicity and accumulation for in vivo biosensing application. However, conventional plasmonic nanostructure on the fiber tip had limitations such as the necessity of expensive fabrication method or hardness for the realization of sufficient plasmonic ‘hot spot’ with cost-effective methods. This research proposed a novel fiber optic SERS probe with multiple strong plasmonic ‘hot spots’ on the fiber tip by gold nanoislands using cost-effective repeated solid-state dewetting of thin gold film. Proposed fiber optic SERS probe enables 100nM limit of detection (LOD) for crystal violet molecules. Furthermore, detection of 1μM folic acid known as a cancer biomarker was successful. Proposed fiber optic probe will provide opportunities for in vivo biosensing using fiber through SERS measurement.