To investigate antioxidant activity of the culture broth from submerged culture of Tremella fuciformis, we preferentially analyzed the chemical composition of culture broth, which was mainly composed of carbohydrate (296.39 mg/g) and protein (9.24 mg/g), respectively. Also, contents of polyphenols, flavonoids and flavonols were 16.63 mg/g, 9.19 mg/g and 83.74 ${mu}/g$, respectively. Next, we examined the scavenging abilities on DPPH (1,1-diphenyl-2-picrylhydrazyl) radical, ABTS (2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid) radical, the reducing power, and chelating ability on ferrous ions. All antioxidant activities of the culture broth were increased in proportion to its concentrations. The $IC_{50}$ values were in order as follows ABTS radical scavenging activity < OPPH radical scavenging activity < chelating power. Accordingly, these results suggest that pharmacological function of T. fuciformis might be due to, at least partially, their protective effects against oxidation and the culture broth of T. fuciformis was free radical inhibitors or scavengers at low concentration, involving possibly in termination of free radical reaction as primary antioxidants.