Abstract: The present disclosure relates to a serum exosomal SF3B4 marker composition for diagnosing early stage hepatocellular carcinoma for noninvasive in vitro diagnosis, wherein, by analyzing an expression level of SF3B4 in plasma proteins as well as expression of SF3B4 in exosomes present in sera of hepatocellular carcinoma patients, the possibility as the most suitable liquid biopsy marker was identified, and a new noninvasive biomarker with high diagnostic accuracy in early stage hepatocellular carcinoma for which no reliable biomarker exists at this present was discovered. As such, by using exosomes to identify cancer cell genomes and proteomes without biopsy, the exosomes are highly applicable in the future as a diagnostic biomarker that is useful in a disease group with a high risk in the biopsy such as hepatocellular carcinoma.